Armed Conflict in Syria: Overview and U.S. Response

September 21, 2018 (RL33487)
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The Syria conflict, now in its eighth year, remains a significant policy challenge for the United States. U.S. policy toward Syria in the past several years has given highest priority to counterterrorism operations against the Islamic State (IS, also known as ISIL/ISIS), but also has included nonlethal assistance to opposition-held communities, support for diplomatic efforts to reach a political settlement to the civil war, and the provision of humanitarian assistance in Syria and surrounding countries. The counter-IS campaign works primarily "by, with, and through" local partners trained, equipped, and advised by the U.S. military, per a broader U.S. strategy initiated by the Obama Administration and modified by the Trump Administration. The United States also has advocated for a political track to reach a negotiated settlement between the government of Syrian President Bashar al Asad and opposition forces, within the framework of U.N.-mediated talks in Geneva. For a brief conflict summary, see Figure 2.

In November 2017, Brett McGurk, Special Presidential Envoy for the Global Coalition to Counter ISIS, stated that the United States was entering a "new phase" in its approach to Syria that would focus on "de-escalating violence overall in Syria through a combination of ceasefires and de-escalation areas." The Administration supported de-escalation as a means of creating conditions for a national-level political dialogue among Syrians culminating in a new constitution and U.N.-supervised elections. However, since mid-2017, the Asad government has retaken several opposition-held areas of Syria, including cease-fire and de-escalation areas. This appears to have significantly reduced pressure on the regime to make concessions to the opposition, with uncertain implications for the outcome of any future political dialogue. Meanwhile, U.S.-backed forces recaptured the Islamic State's self-proclaimed capital at Raqqah in October 2017, and have since retaken most other areas formerly under IS control in eastern Syria.

With the IS threat diminished and the Asad government resurgent, President Trump and Administration officials have sent varying messages about U.S. Syria policy. Officials emphasize that the United States is committed to the enduring defeat of the Islamic State and will not contribute to reconstruction in Asad-held areas unless a political solution is reached in accordance with U.N. Security Council Resolution 2254. Questions remain about the extent to which U.S. forces might remain in Syria and specific U.S. assistance plans. The Administration has ended nonhumanitarian U.S. support to opposition-controlled northwest Syria and has obtained foreign contributions to enable the reprogramming of U.S. funds that Congress appropriated to stabilize areas liberated from the Islamic State. The FY2019 National Defense Authorization Act (P.L. 115-232) requires the Administration to clarify its Syria strategy and report on current programs in order to obligate FY2019 defense funds for train and equip purposes in Syria.

To date, the United States has directed more than $8.6 billion toward Syria-related humanitarian assistance, and Congress has appropriated billions more for security and stabilization initiatives in Syria and in neighboring countries. The Defense Department has not disaggregated the costs of military operations in Syria from the overall cost of Operation Inherent Resolve (OIR), which, as of March 2018, had reached $23.5 billion. President Trump requested $15.3 billion in additional FY2019 defense funding for OIR. Congress continues to consider proposals to authorize or restrict the use of force against the Islamic State and in response to Syrian government chemical weapons attacks, but has not enacted any Syria-specific use of force authorizations.

Looking forward, Congress may consider the purpose, scope, authorization, and duration of the U.S. military presence in Syria, the U.S role in ensuring a lasting defeat for the Islamic State and other extremists, U.S. investments and approaches to postconflict stabilization, the future of Syrian refugees and U.S. partners inside Syria, and the challenges of dealing with the Iran- and Russia-aligned Asad government.


In March 2011, antigovernment protests broke out in Syria, which has been ruled by the Asad family for more than four decades. The protests spread, violence escalated (primarily but not exclusively by Syrian government forces), and numerous political and armed opposition groups emerged. In August 2011, President Barack Obama called on Syrian President Bashar al Asad to step down. Over time, the rising death toll from the conflict, and the use of chemical weapons by the Asad government, intensified pressure for the United States and others to assist the opposition. In 2013, Congress debated lethal and nonlethal assistance to vetted Syrian opposition groups, and authorized the latter. Congress also debated, but did not authorize, the use of force in response to an August 2013 chemical weapons attack.

In 2014, the Obama Administration requested authority and funding from Congress to provide lethal support to vetted Syrians for select purposes. The original request sought authority to support vetted Syrians in "defending the Syrian people from attacks by the Syrian regime," but the subsequent advance of the Islamic State organization from Syria across Iraq refocused executive and legislative deliberations onto counterterrorism. Congress authorized a Department of Defense-led train and equip program to combat terrorist groups active in Syria, defend the United States and its partners from Syria-based terrorist threats, and "promot[e] the conditions for a negotiated settlement to end the conflict in Syria."

In September 2014, the United States began air strikes in Syria, with the stated goal of preventing the Islamic State from using Syria as a base for its operations in neighboring Iraq. In October 2014, the Defense Department established Combined Joint Task Force-Operation Inherent Resolve (CJTF-OIR) to "formalize ongoing military actions against the rising threat posed by ISIS in Iraq and Syria." CJTF-OIR came to encompass more than 70 countries, and has bolstered the efforts of local Syrian partner forces against the Islamic State. The United States also gradually increased the number of U.S. personnel in Syria, which reached roughly 2,000 by late 2017. President Trump in early 2018 called for an expedited withdrawal of U.S. forces from Syria,1 while other Administration officials have stated that a continued U.S. presence is key to preventing the reemergence of the Islamic State.

U.S. and coalition-backed forces in Syria succeeded in retaking, from 2015 through mid-2018, nearly all of the territory once held by the Islamic State. Meanwhile, other outside actors (Lebanese Hezbollah, Iran, and Russia) continued to support the Syrian government's military campaigns against opposition groups. Conflict between the coalition's Syrian partners and other U.S. allies has further complicated the situation, as have the growth of Al Qaeda-affiliated groups among the opposition and the ongoing humanitarian crisis. As of mid-2018, more than 5.6 million Syrians have fled to nearby countries, with 6 million more internally displaced inside Syria.

The collapse of IS and opposition territorial control in most of Syria since 2015 has been matched by significant military and territorial gains by the Syrian government. The U.S. intelligence community's 2018 Worldwide Threat Assessment stated in February 2018 that,

The conflict has decisively shifted in the Syrian regime's favor, enabling Russia and Iran to further entrench themselves inside the country. Syria is likely to experience episodic conflict through 2018, even as Damascus recaptures most of the urban terrain and the overall level of violence decreases.2

The U.N. has sponsored peace talks in Geneva, but it is unclear when (or whether) the parties might reach a political settlement that could result in a transition away from Asad. With many armed opposition groups weakened, defeated, or geographically isolated, military pressure on the Syrian government to make concessions to the opposition has been reduced. U.S. officials have stated that the United States is committed to the enduring defeat of the Islamic State and will not fund reconstruction in Asad-held areas unless a political solution is reached in accordance with U.N. Security Council Resolution 2254.3 Congress is considering legislation that would condition the use of U.S. funds in Asad-controlled areas for nonhumanitarian purposes and has directed the Administration to report to Congress on its strategy.

Figure 1. Syria: Map and Country Data


Size: 185,180 sq km (slightly larger than 1.5 times the size of Pennsylvania)

General Demographics

Population: 18 million (July 2017 est.)

Religions: Muslim 87% (Sunni 74% and Alawi, Ismaili, and Shia 13%), Christian 10%, Druze 3%

Ethnic Groups: Arab 90.3%, Kurdish, Armenian, and other 9.7%

Gross Domestic Product (GDP; growth rate): $24.6 billion (2014 est.); -36.5% (2014 est.)

Indicators of Humanitarian Need

People in need of humanitarian assistance: 13.1 million

Internally displaced persons: 6.6 million

Syrian refugees: 5.6 million

Unemployment rate: 50% (2017 est.)

Population living in extreme poverty: 69% (2018 est., UNOCHA)

Figure 2. Syria Conflict 2011-2017

Source: For sourcing and additional details, see Appendix A ("Conflict Synopsis").

Figure 3. Syria Areas of Influence 2018

As of August 27, 2018

Source: CRS using area of influence data from IHS Conflict Monitor, last revised August 27, 2018. All areas of influence approximate and subject to change. Other sources include U.N. OCHA, Esri, and social media reports.

Notes: U.S. military officials have acknowledged publicly that U.S. forces are operating in select areas of eastern Syria to train, advise, assist, and equip partner forces. This map does not depict all chemical attacks reported in Syria.

Figure 4. Syria Areas of Influence 2017

As of August 1, 2017

Source: CRS using area of influence data from IHS Conflict Monitor, as of August 1, 2017. All areas of influence approximate. Other sources include U.N. OCHA, Esri, and social media reports.

Notes: U.S. military officials have acknowledged publicly that U.S. forces are operating in select areas of eastern Syria to train, advise, assist, and equip partner forces. This map does not depict all chemical attacks reported in Syria.

Issues for Congress

Congress has considered the following key issues since the outbreak of the Syria conflict in 2011:

Amid significant territorial losses by the Islamic State and Syrian opposition groups since 2015 and parallel military gains by the Syrian government and coalition partner forces, U.S. policymakers face a number of questions and potential decision points related to the following factors:

The future of U.S. relations with the Asad government. Strained U.S.-Syria ties prior to the start of the conflict were reflected in a series of U.S. sanctions and legal restrictions that remain in place today. U.S. policy toward Syria since August 2011 has been predicated on a stated desire to see Bashar al Asad leave office, preferably through a negotiated political settlement. Nevertheless, the Asad government—backed by Russia and Iran—has reasserted control over much of western Syria since 2015, and appears poised to claim victory in the conflict. The Trump Administration has stated its intent to refrain from supporting reconstruction efforts in Syria until a political solution is reached in accordance with UNSCR 2254, which calls for constitutional reform and U.N.-supervised elections. The Trump Administration emphasizes that in its view the primary U.S. interest in Syria is achieving the enduring defeat of the Islamic State, but the Administration also identifies other goals, including reducing Iranian influence in the country, addressing issues raised by displaced Syrians, and achieving a durable solution to the underlying conflict. With Asad and his allies ascendant, Members of Congress and U.S. policymakers may consider whether future U.S. policy approaches should seek to end U.S. involvement in Syria altogether, define and proceed with conditional engagement, or contain or coerce an Asad-led Syrian government. In the short term, discussions may focus on whether or how the Syrian government's reassertion of de facto control should affect U.S. military and assistance policy. U.S. partner forces and assistance recipients face their own difficult choices about whether or how to reconcile themselves with Asad and his backers.

U.S. military operations and the presence of U.S. military personnel in Syria. U.S. and coalition military operations against Islamic State forces in Syria continue in areas of eastern Syria close to the Iraqi border. These operations have been conducted in part at the request of Iraq's government for international military support in addressing threats emanating from Syria, in light of the Syrian government's inability or unwillingness to address those threats. With the formation of a new government in Iraq underway and the Asad government's more capable and assertive posture in Syria, some parties may seek to revisit and revise the prevailing international legal framework for ongoing coalition operations in Syria. As Administration officials proceed with new U.S. policy initiatives, Congress is also seeking clarification regarding how long U.S. military personnel will remain in Syria, for what purposes, and under what conditions they may be withdrawn.4

The future of the Syria Train and Equip program. The Islamic State has lost the vast majority of the territory it once held in Syria, and much of that territory is now controlled by U.S.-backed local forces (see Figure 3 and Figure 4). The significant reduction of IS territorial control has prompted some reevaluation of the Syria Train and Equip (T&E) program, whose primary purpose has been to support offensive campaigns against Islamic State forces. The FY2017 National Defense Authorization Act (NDAA) extended the program's authority through the end of 2018, but the FY2018 NDAA did not extend it further, asking instead for the Trump Administration to submit a report on its proposed strategy for Syria by February 2018. That strategy has yet to be submitted, and the FY2019 NDAA (P.L. 115-232) prohibits the obligation of FY2019 defense funds for the program until the strategy and an additional update report on train and equip efforts are submitted to Congress. The FY2019 act extends the Syria T&E authority through December 2019 but does not adjust the program's authorized scope or purposes. The Trump Administration requested $300 million in FY2019 Counter-ISIS Train and Equip Fund (CTEF) monies for Syria programs, and the House-passed and Senate-reported versions of the FY2019 defense appropriations act (H.R. 6157 and S. 3159) would appropriate different amounts for the account generally and for Syria programs specifically.

The future of U.S. assistance and stabilization programs. The Trump Administration has directed a reorientation in U.S. assistance programs in Syria and has sought and received new foreign contributions to support the stabilization of areas liberated from Islamic State control. The practical effect of this approach to date has been the drawdown of some assistance programs in opposition-held areas of northwestern Syria and the reprogramming of some U.S. funds appropriated by Congress for stabilization programs in Syria to other priorities. The future of U.S. assistance programs in formerly opposition-held areas of southern and southwestern Syria also is in question, in light of the Asad government's reassertion of control in these areas. As noted above, the Administration has stated its intention to end nonhumanitarian assistance to Asad-controlled areas of the country until the Syrian government fulfills the terms of UNSCR 2254.

U.N. Special Envoy for Syria Staffan de Mistura said in 2017 that Syria reconstruction will cost at least $250 billion.5 The Trump Administration has stated its intent to use U.S. diplomatic influence to discourage other international assistance to government-controlled Syria in the absence of a credible political process.6 Congress may debate how the United States might best assist Syrian civilians in need, most of whom live in areas under Syrian government control, without inadvertently strengthening the Asad government or its Russian and Iranian patrons.

Select Proposed Syria-Related Legislation

In addition to provisions of FY2018 and FY2019 Foreign Operations and Defense Appropriations Acts and National Defense Authorization Acts that address some of the questions and issues described above, the 115th Congress has considered other legislation related to Syria, including the following:

H.R. 4681, No Assistance for Assad Act. Passed by the House in April 2018, the bill would state that it is the policy of the United States that reconstruction and stabilization assistance is to be provided only to "a democratic Syria" or to areas of Syria not controlled by the Asad government, as determined by the Secretary of State. Reconstruction aid appropriated or otherwise available from FY2019 through FY 2023 could be provided "directly or indirectly" to areas under Syrian government control only if the President certifies to Congress that the government of Syria (1) has ceased attacks against civilians and civilian infrastructure, (2) is taking steps to release all political prisoners, (3) is taking steps to remove senior officials complicit in human rights abuses, (4) is in the process of organizing free and fair elections, (5) is making progress toward establishing an independent judiciary, (6) is complying with human rights, (7) is taking steps toward fulfilling its commitments under international agreements that regulate the proliferation of chemical and nuclear weapons, (8) has halted the development and deployment of ballistic and cruise missiles, (9) is taking steps to remove government officials complicit in torture, extrajudicial killings, or chemical weapons use, (10) is reforming the military and security services to minimize the role of Iran and Iranian proxies, and (11) is in the process of securing the voluntary return of refugees and internally displaced persons.

By noting restrictions on U.S. aid provided "directly or indirectly," the bill also would limit U.S. funds that could flow into Syria via multilateral institutions and international organizations, including the United Nations, the International Monetary Fund, and the World Bank. From 2014 through 2017, appropriations acts authorized the provision of certain types of U.S. assistance to Syria for stated purposes notwithstanding any other provisions of law, without limits based on territorial control or Syrian government policy. A range of restrictions on U.S. assistance to Syria otherwise remains in place as a result of preconflict U.S. sanctions on the Asad government.

The bill would permit exceptions to the above restrictions on aid to government-held areas for

Such projects would require the President to submit a report to appropriate congressional committees.

Additionally, the bill would require a report from the State Department and the United States Agency for International Development (USAID) describing the delivery of U.S. humanitarian assistance to Syria, including access restrictions and the monitoring and evaluation of implementing partners.

Authorization for Use of Military Force of 2018 (AUMF, S.J.Res. 59). Introduced on April 16, 2018, S.J.Res. 59 would include an authorization that is intended to provide the President the authority and flexibility he determines is necessary to carry out counterterrorism operations and protect U.S. national security by continuing to respond to the threat posed by Al Qaeda, the Islamic State, the Taliban, and other groups. It also aims to ensure that Congress exercises its legislative and oversight responsibilities with regard to its purview within the war powers enshrined in the Constitution and shared between the legislative and executive branches. Section 5(a) of S.J.Res. 59 would provide a specific list of additional designated associated forces targetable under its authorization, including Al Qaeda in Syria and the Nusra Front. The resolution would recognize Syria as a country where the use of military force is already taking place.

Caesar Syria Civilian Protection Act of 2017 (H.R. 1677). Passed by the House in May 2017, the bill updates and amends legislation (H.R. 5732) passed by the House in the 114th Congress, incorporating provisions from other proposed legislation and appearing to address some concerns expressed by various Syria policy stakeholders.

As amended, H.R. 1677 would state that "It is the policy of the United States that all diplomatic and coercive economic means should be utilized to compel the government of Bashar al-Assad to immediately halt the wholesale slaughter of the Syrian people and to support an immediate transition to a democratic government in Syria that respects the rule of law, human rights, and peaceful coexistence with its neighbors." The bill would authorize the imposition of certain sanctions by the President and amend current law to require the President to impose other sanctions on individuals he designates as eligible. The bill would require the President to submit an updated report on individuals alleged to be responsible for "serious human rights abuses" in Syria, which the bill would amend current law to define. In defining "serious human rights abuses" and requiring the Administration to report on the responsibility of dozens of named individuals for such abuses, the bill appears to create a dynamic that would make it more difficult for the executive branch to decline to designate Syrian individuals for human rights-based sanctions.

The bill would expand the potential scope of existing U.S. sanctions on Syria by making parties engaged in certain transactions with, or in support of, the government of Syria eligible for sanctions. Current executive orders impose such sanctions in some cases. The sanctions authorized in the bill could be imposed on individuals determined by the President to have met designated criteria because of knowing engagement in actions "on or after" the date of enactment. The sanctions would thus be prospective rather than retrospective. The sanctions authorized could be imposed on U.S. nationals and non-nationals. A large number of individuals are already subject to U.S. Syria-related sanctions, and in some cases individuals may already be subject to U.S. sanctions for engaging in transactions with sanctioned individuals, including entities in Russia and Iran that provide military support to the Syrian government.

The bill would require a report within 90 days assessing the potential effectiveness, risks, and operational requirements of establishing and maintaining a no-fly zone over part or all of Syria, and establishing one or more safe zones in Syria for internally displaced persons or for facilitating humanitarian assistance. It would also codify authorization for certain services in support of nongovernmental organizations' activities in Syria.

The bill includes a national security waiver and negotiation or transition scenario-specific waiver authorities for the President. Its provisions would expire after December 31, 2021.

Preventing Destabilization of Iraq and Syria Act of 2017. In January 2017, Senators Rubio and Casey introduced S. 138, known as the Preventing Destabilization of Iraq and Syria Act of 2017. They had previously introduced the bill in December 2016 as S. 3536 (114th Congress), known as the Preventing Destabilization of Iraq and Syria Act of 2016. The bill incorporated many aspects of H.R. 5732 (114th Congress), including the requirement for the imposition of sanctions on the Central Bank of Syria as well as on foreign individuals that provide support for the Syrian government or for the maintenance or expansion of natural gas and petroleum production in Syria. In addition, it would require the imposition of sanctions on Syrians complicit in the blocking of humanitarian aid.

The bill also would authorize the President to provide enhanced support for humanitarian activities in Syria, including the provision of food, shelter, water, health care, and medical supplies. It would prohibit the President from imposing sanctions on a foreign financial institution for engaging in a transaction with the Central Bank of Syria for the sale of food, medicine, medical devices, donations intended to relieve human suffering, or nonlethal aid to the people of Syria. It further would prohibit the President from imposing sanctions on internationally recognized humanitarian organizations for engaging in financial transactions related to the provision of humanitarian assistance, or for having incidental contact (in the course of providing humanitarian aid) with individuals under the control of foreign persons subject to sanctions under the act.

Conflict Developments

The conflict between pro-Syrian government and opposition forces contains a variety of secondary dynamics, many of which have been exploited by outside actors. Political and armed opposition groups differ on both strategy and ideology. The opposition's Arab majority maintains a tense relationship with the most powerful Syrian Kurdish groups, which seek greater autonomy and control in significant portions of northern Syria. Armed groups have clashed with U.S.-designated foreign terrorist organizations (FTOs), which have also fought among themselves (the Islamic State and Al Qaeda). In addition to the United States, regional and global actors—such as Hezbollah, Iran, Russia, Turkey, and the Gulf States—have intervened in Syria, bolstering various sides in the conflict in order to further their own interests. In this process, U.S. adversaries have clashed with U.S. allies, and U.S. allies have clashed with local U.S. partners. The section below summarizes key military and political developments in the Syria conflict, but is not comprehensive.


Idlib: The Final Opposition Stronghold

Idlib province, in Syria's northwest, has been a stronghold of opposition support since the early months of the conflict; opposition fighters seized control of the entire province in March 2015. U.S. officials have described the province as a safe haven for Al Qaeda, while highlighting the presence of thousands of civilians displaced to Idlib from other parts of the country. In May 2017, the province was declared a de-escalation area, a move designed to reduce violence between regime and opposition forces. However, regime forces continued to pursue military operations in Idlib, recapturing about half the province by mid-2018. Both regime and armed opposition forces expressed determination to control the remaining portions of Idlib, raising fears that a large-scale offensive pitting Syrian government forces against a mix of armed opposition and jihadist forces could trigger a humanitarian crisis for civilians in the area. In September 2018, Russia and Turkey announced plans to create a demilitarized zone in parts of Idlib province.

Potential Humanitarian Crisis

In September, U.N. Under-Secretary-General for Humanitarian Affairs and Emergency Relief Coordinator Mark Lowcock stated that a mass assault on Idlib could result in "the biggest humanitarian catastrophe we've seen for decades—certainly the biggest in the 21st century."7 The U.N.'s Commission of Inquiry on Syria has described conditions for civilians in Idlib as "dire," and stated, "Conflicting parties must cease and refrain from the future use of indiscriminate weapons or tactics to target thousands of fighters interspersed among 2.9 million civilians, including one million children."8

The Syrian government has transferred thousands of Islamist and other fighters and their families to Idlib as part of surrender agreements with opposition-held towns in other parts of the country. A U.N. official in June 2018 described Idlib as a regime "dumping ground" for civilians and fighters evacuated from other opposition-controlled areas.9 Extremist groups and some opposition fighters that have been relocated to the province after rejecting surrender agreements elsewhere are expected to forcefully resist any Syrian government campaign. At the same time, the wide-scale use of military force by the Syrian government and its supporters against opposition-held areas of Idlib would likely result in significant civilian casualties and displacement.

Al Qaeda in Idlib

U.S. officials in mid-2017 described Idlib province as "the largest Al Qaeda safe haven since 9/11."10 Beginning in 2014, the United States conducted a series of airstrikes, largely in Idlib province, against Al Qaeda targets. These strikes fell outside the framework of Operation Inherent Resolve (which focuses on the Islamic State), and U.S. officials stated that they were conducted on the basis of the 2001 AUMF.11 At least a dozen foreign Al Qaeda leaders have been killed in Syria since 2014, mostly in Idlib. A February 2017 U.S. drone strike in Idlib killed the deputy leader of Al Qaeda, and a U.S. strike on an Al Qaeda training camp in Idlib the previous month killed more than 100 Al Qaeda fighters.12 As of 2018, Al Qaeda fighters and supporters appear to have merged into various opposition coalitions.

Armed Coalition Groups Operating in Idlib

Hay'at Tahrir al Sham (HTS). In 2016, the Nusra Front declared a split with Al Qaeda and changed its name to Jabhat Fatah al Sham (JFS, Levant Conquest Front)—a move dismissed by U.S. government officials and other observers at the time as a rebranding effort. In 2017, JFS merged with other groups and changed its name to Hay'at Tahrir al Sham (HTS, Levant Liberation Committee). U.S. officials have stated that "The core of HTS is Nusra,"13 and amended the FTO designation of the Nusra Front in May 2018 to include HTS as an alias. However, some analysts argue that statements by Al Qaeda leader Ayman al Zawahiri and actions by Nusra and HTS members point to the emergence of a genuine rift within the two groups. This rift can be seen, they argue, in the defection of former Nusra Front members from HTS, and the arrests by HTS of senior Al Qaeda figures.14 In addition to its military operations, HTS also runs a civilian-led "Salvation Government," based in Idlib, which provides services such as education, health care, electricity, and water.

National Liberation Front (NLF). In May 2018, 11 Syrian armed groups established the NLF coalition. A NLF spokesperson described the coalition as unifying a number of "Free Syrian Army factions."15 The group has been described as one of the largest coalitions fighting the Asad government, reportedly reaching nearly 30,000 fighters.16 In August, the Syrian Liberation Front (SLF), composed of fighters from armed Islamist groups Ahrar al Sham (Free Men of the Levant) and the Nour al Din al Zinki Movement, merged into the NLF.

Hilf Nusra al Islam. In April 2018, Horas al Din (Guardians of Religion) and Ansar al Tawhid (Supporters of Monotheism, formerly known as Jund al Aqsa, or Army of Al Aqsa) merged to form Hilf Nusra al Islam (Alliance for the Support of Islam).17 The group is viewed as sympathetic to Al Qaeda.

The Role of External Actors

The May 2017 agreement at Astana that established the three de-escalation areas (including Idlib) set Russia, Turkey, and Iran as guarantors. The situation in Idlib has highlighted potentially diverging interests among them, with Turkey seeking to prevent a Syrian military operation that could weaken its control over key swaths of northern Syria and/or result in a large-scale refugee influx across its border, and Russia and Iran focusing on the eradication of armed opposition groups in the province.

Turkey. Idlib lies along Turkey's southern border. U.N. officials have expressed concern that a military offensive by Syria to retake the province could force as many as 2.5 million people to seek refuge in Turkey, which already hosts around 3.5 million Syrian refugees. Turkey has played a significant role in Idlib, maintaining 12 military observation posts in and around Idlib province along the "separation line" between pro-Syrian government and opposition forces. In September 2018, Turkey reportedly began to reinforce its military outposts in Idlib in advance of a potential Syrian government offensive.18

Turkey maintains ties with a range of Syrian opposition groups in the province—reportedly including HTS, a U.S.-designated FTO.19 Analysts have noted Turkish efforts to target "hardline" HTS fighters while maintaining ties to elements of the group seen as more moderate.20 Some argue that Turkey may seek to fracture and eventually dissolve HTS by peeling off "moderate" fighters from the group.21 Turkey's coordination with rebel groups in northern Syria appears to be driven primarily by Ankara's desire to minimize, if not completely roll back, Syrian YPG control of areas along Turkey's border. In turn, Syrian armed groups ally with Turkey for reasons that may include (1) material and financial support; (2) protection against the advance of Syrian military forces; and (3) an opportunity to counter perceived Kurdish expansion in traditionally Arab areas of northern Syria as part of the counter-IS campaign.

Russia. In September, Russia's foreign minister stated that Russia would continue to target what he described as "terrorist weapons-making facilities" in Idlib, while also encouraging local reconciliation deals.22 Since early 2018, Russian officials have expressed concern about drone strikes, launched from Idlib, which have targeted Russian military facilities in neighboring Lattakia province. However, a wide-scale offensive on Idlib province could pose significant challenges for Russia, and Russian officials have at times described such an operation as "out of the question."23 According to one analysis,

Given the mountainous terrain; the broadly dispersed and largely rural population; the scale of armed opposition numbers and marbled presence of experienced and committed jihadists; and the sheer size of the civilian and internally displaced population, any campaign to retake Idlib by force would likely require a far greater Russian military effort than anything Moscow has undertaken in Syria thus far.24

However, recent Russian strikes in Idlib suggest that Moscow may be prepared to undertake a limited military campaign, in the absence of agreements that meet its demands. Russia has pressed Turkey to work with opposition groups in Idlib to eliminate radical militants.25 In August, Russia's special envoy for Syria stated,

… we encouraged the moderate opposition to actively cooperate with Turkish partners and with Russia—to prevent any danger both for Russian soldiers of the Khmeimim air base and for Syrian government forces staying on the line of contact. In this case, we will not have to engage in full-blown fighting against militants.26

Russia and Turkey Agree on Idlib De-militarized Zone

On September 17, Russia and Turkey announced that they planned to establish a 9- to 12-mile-wide demilitarized zone in Idlib province by October 15. The zone reportedly will separate areas controlled by the regime from areas controlled by armed opposition forces, and will be monitored by coordinated patrols by Russian and Turkish military police.27 The agreement calls for the removal of heavy weapons and "radical terrorist groups" and from the de-militarized zone by October 10 and October 15, respectively, but officials did not describe how this would be accomplished.28 Officials also did not specify how and by whom the continued presence of "terrorist groups" or heavy weaponry after the October deadlines might be assessed, or what consequences would follow from noncompliance.

The agreement calls for the restoration of traffic along the M4 (Aleppo-Lattakia) and M5 (Aleppo-Hamah) highways by 2018. Full restoration of regime control over these transit arteries would effectively split opposition-held areas of Idlib into three sectors, facilitating any eventual military campaign in the province.

Southern Syria: Asad Retakes Southwest Cease-fire Area

In July 2018, Syrian military forces recaptured the southwest cease-fire area. Also known as the southwest de-escalation zone, the area was established in July 2017 through an agreement between the United States, Russia, and Jordan. The area covered the majority of Dar'a province, including areas adjacent to the Israeli-occupied Golan Heights and the Jordanian border. (See Figure 5.) In the spring of 2018, dozens of armed groups operated in and around the southwest cease-fire area. These included U.S.-designated foreign terrorist organizations such as HTS and Jaysh Khalid Ibn al Walid,29 but also the Southern Front—a coalition of roughly 50 factions which reportedly had received Western support.30

In May 2018, U.S. officials expressed concern about reports of an impending Syrian regime operation within the de-escalation zone, stating "As a guarantor of this de-escalation area with Russia and Jordan, the United States will take firm and appropriate measures in response to Asad regime violations."31 According to some reports, U.S. officials also privately warned Southern Front rebels not to expect U.S. backing if they broke the terms of the cease-fire agreement.32

Figure 5. Southwest Cease-fire Area

Source: Created by CRS.

Opposition groups surrender following Russia-brokered cease-fire deal

Following weeks of government airstrikes, artillery, and rocket attacks in the cease-fire area, some opposition forces on July 6 accepted a surrender accord brokered by Russia, and agreed to relinquish heavy weapons to the Syrian government.33 Syrian military forces also seized control of the Nasib border crossing with Jordan, which had been held by rebels since 2015. As with prior surrender agreements elsewhere in the country, oppositionists unwilling to accept renewed Asad rule were transferred to opposition-held areas of northwest Syria. The Islamic State-affiliated Jaysh Khalid Ibn al Walid was not a party to the July 6 surrender and continued to target Syrian military forces and opposition groups in Quneitra and Dar'a provinces. On July 25, 2018, the Islamic State conducted a series of coordinated attacks in the provincial capital of Suweida, just east of the southwest cease-fire area. The attacks killed more than 200 people.34

On July 31, Syrian government forces recaptured the remaining portion of the southwest cease-fire area, reaching the border with the Israeli-occupied Golan Heights. The Syrian government reportedly granted safe passage to dozens of IS-affiliated fighters from Jaysh Khalid Ibn al Walid to the Badia desert area in southeastern Syria, in exchange for hostages held by the group.35 U.S. forces maintain a base of operations in the Badia area near the At Tanf border crossing with Iraq (see Figure 3).

Israeli Strikes in Syria

Israel has conducted dozens of air strikes inside Syria since 2012—mostly on locations and convoys near the Lebanese border associated with weapons shipments to Lebanese Hezbollah.36 In September 2018, Israeli Intelligence Minister Israel Katz said, "in the last two years Israel has taken military action more than 200 times within Syria itself."37 In 2018, strikes widely attributed to Israel have, for the first time, directly targeted Iranian facilities and personnel in Syria.38

The expanding presence of Iranian and Iranian-backed personnel in Syria has remained a consistent point of tension between Israel and Iran. In June 2018, Israel conducted a strike near Abu Kamal,39 along Syria's eastern border with Iraq. The strike was far beyond Israel's usual operational range—Israel had not struck inside Deir ez Zor province since its 2007 strike on the Al Kibar nuclear reactor.40 The June strike appeared to target Iran-backed militia fighters.

Additional Israeli strikes in Syria were reported in August and September. On September 17, Israel struck military targets in Syria's coastal province of Lattakia. A Syrian antiaircraft battery responding to the Israeli strikes downed a Russian military plane, killing 15 Russian personnel.41 An IDF spokesperson stated that Israeli jets were targeting "a facility of the Syrian Armed Forces from which systems to manufacture accurate and lethal weapons were about to be transferred on behalf of Iran to Hezbollah in Lebanon."42 The spokesperson added that the IDF and the Russian military maintain a deconfliction system in Syria, stating that the Russian plane was not in the area of operation during the Lattakia strike and blaming "extensive and inaccurate" Syrian antiaircraft fire for the incident.

For additional information on reported Israeli strikes in Syria, see Appendix B. See also, CRS In Focus IF10858, Iran and Israel: Growing Tensions Over Syria, by [author name scrubbed], [author name scrubbed], and [author name scrubbed].

Syrian Government Retakes Two Astana De-escalation Areas

In May 2017, Russia, Iran, and Turkey designated three opposition-held areas as "de-escalation" zones: eastern Ghouta in the Damascus suburbs, some parts of northern Homs province, and Idlib province and its surroundings. (See "The Astana Process.") The May 2017 agreement, designed to reduce violence in those areas between regime and opposition forces, allowed for states to "continue the fight" against extremist groups. Syria and Russia have traditionally labeled all groups opposing the Syrian regime as "terrorist." On that basis, they escalated military operations against opposition forces based in the de-escalation areas, and by mid-2018 had recaptured eastern Ghouta, northern Homs, and portions of Idlib province.

Eastern Ghouta

The enclave of eastern Ghouta consists of several towns within the Ghouta oasis on the outskirts of Damascus. The area's significance to the Syrian government stems from various factors including the following: (1) the M-5 highway (Syria's primary north-south artery) runs through it, linking the primary commercial land crossings with Jordan to Dar'a City, and onward to Damascus; (2) prior to the war, the area supplied the capital with agricultural, manufactured, and industrial goods; and (3) opposition groups were able to use the area to stage rocket and mortar attacks on central Damascus.

Eastern Ghouta fell under opposition control in 2012, and Syrian military forces besieged the area in 2013, limiting the ability of civilians to flee and restricting deliveries of food, medicine, and fuel.43 The Syrian military conducted numerous air strikes in the area, and in 2013 carried out a sarin gas attack that killed 1,400 people (see "Overview: Syria Chemical Weapons and Disarmament"). In October 2017, U.N. High Commissioner for Human Rights Zeid Ra'ad Al Hussein called the situation of besieged civilians in eastern Ghouta "an outrage," saying "the deliberate starvation of civilians as a method of warfare constitutes a clear violation of international humanitarian law and may amount to a crime against humanity and/or a war crime."44 In January 2018, then-Secretary of State Tillerson condemned what he described as "an apparent chlorine gas attack" in eastern Ghouta.45

In February 2018, Syrian government forces intensified their attacks on eastern Ghouta in what U.N. officials described as "some of the worst fighting of the entire conflict."46 By late March, over 1,700 people had reportedly been killed and an estimated 80,000 civilians had been displaced, overwhelming the capacity of shelters in the Damascus area.47 Facing intense aerial attack, most armed groups operating in eastern Ghouta withdrew in late March under agreements negotiated by Russia. Fighters agreed to evacuate the area in exchange for safe passage to the northern province of Idlib. The withdrawal left only Douma, eastern Ghouta's largest city, under the control of opposition groups (Jaysh al Islam).

On April 7, Syrian government forces launched a suspected chemical attack on Douma, killing at least 40 people and triggering U.S. airstrikes on chemical weapons and storage sites in Syria (see "2018 Chemical Attack (Douma) and U.S. Response"). On April 8, Jaysh al Islam fighters in Douma agreed to a Russian-sponsored evacuation deal granting them safe passage to the city of Jarabulus in northern Aleppo province.48 In exchange, fighters agreed to release hundreds of Syrian military prisoners of war.

Northern Homs

After capturing eastern Ghouta, the regime turned its focus to the de-escalation area in northern Homs province. The area includes the towns of Rastan and Talbiseh, strongholds of opposition support and home to many army defectors. It also includes the area around the Houla Plain, site of an early 2012 massacre. Rastan and Talbiseh sit along the portion of the M-5 highway that connects the provincial capitals of Hamah and Homs, and the opposition's hold over these towns restricted regime mobility in and through the area. Following airstrikes and shelling by Syrian military forces, a cease-fire was announced in late April, and Syrian rebels surrendered the area in early May.49 As in eastern Ghouta, fighters gave up their heavy weapons in exchange for safe passage to northern Idlib province.

Aleppo: Turkish Operations in Afrin; Status of Manbij

In January 2018, Turkey and affiliated Syrian armed groups launched a ground operation and air strikes in the Afrin district of northern Aleppo province. Known as Operation Olive Branch, it targeted forces from the Syrian Kurdish People's Protection Units (YPG), which have administered Afrin since 2012. Turkish officials stated that the operation aimed to stabilize the border region and eliminate PKK, YPG, and IS fighters.50 Turkey has long expressed concern about how counter-IS operations in northern Syria have effectively expanded and entrenched the YPG presence in the area, which borders southern Turkey.

Dispute Over PKK-YPG Ties

Disagreement regarding the status of the YPG remains a key point of discord between Turkey and the United States. Turkey considers the YPG to be the Syrian branch of the PKK (Kurdistan Workers' Party), and thus a terrorist organization. (The PKK has battled the Turkish government on and off since the 1980s.) While both Turkey and the United States have designated the PKK a terrorist organization, the United States has not extended this designation to the YPG, which has been one of the United States' most prominent local partners in the counter-IS campaign. Turkey has accused the United States of backing a terrorist group along Turkey's southern border.

While the YPG forms a key part of the U.S.-backed Syrian Democratic Forces (SDF), U.S. military officials have stated that, "we haven't trained or provided equipment for any of the Kurds that are in the Afrin pocket."51 However, U.S. military officials also described Turkish operations around Afrin as "not helpful," stating that they distract from ongoing operations against Islamic State remnants.52 Some YPG elements battling the Islamic State in eastern Syria shifted west to Afrin following the launch of Operation Olive Branch, prompting U.S. officials in March to declare an "operational pause" in the counter-IS campaign.53

After capturing the surrounding areas, Turkish and allied Syrian groups entered the city of Afrin in March. While expressing commitment to Turkey's "legitimate security concerns," U.S. officials added that they were "deeply concerned" over reports from Afrin city that the majority of the city's population had evacuated "under threat of attack from Turkish military forces and Turkish backed opposition forces."54 The U.N. in June estimated that roughly 134,000 people remain displaced from Afrin district.55

Agreement in Manbij

U.S.-backed SDF forces recaptured the town of Manbij from the Islamic State in 2016. This was followed shortly by Turkish operations north of the city (Operation Euphrates Shield) which sealed the "Manbij pocket" border area to reduce the flow of IS foreign fighters. Turkey has repeatedly called for the departure of remaining Kurdish forces from the city. U.S. officials have described the status of the area as "a fairly tense standoff between certain opposition forces north of the Manbij area and the Syrian Democratic Forces south," noting that the United States has "helped patrol the demarcation line."56 Officials noted that tensions in Manbij increased following Turkish operations in Afrin in 2018, which brought additional refugees and armed groups into Manbij. After the Turkish-backed capture of Afrin in March, Turkish President Recep Tayyip Erdogan indicated that Turkey would push eastward toward Manbij. Later, a Pentagon spokesman said, "It's been very clear to all parties that U.S. forces are there, and we'll take measures to make sure that we de-conflict."57

On June 4, the United States and Turkey endorsed what U.S. officials described as a "broad political framework designed to fulfill the commitment that the United States had made to move the YPG east of the Euphrates."58 As part of the agreement, the United States will continue to patrol the demarcation line. Kurdish fighters who form part of the Manbij Military Council are expected to withdraw from the city, and a new Manbij council will be formed comprised of "locals who are mutually agreeable." U.S. officials stated that the aim behind the agreement is "for the people of Manbij to reassert their leadership over both governance and security structures there."59 As of September 2018, the United States and Turkey continue to conduct "independent coordinated patrols" outside Manbij, and U.S. military officials have stated that "very little YPG if any at all" remain inside the city.60

Northeast Syria: Ongoing Counter-IS Operations

On May 1, 2018, SDF forces launched the first phase of Operation Roundup, targeting IS remnants in the Middle Euphrates River valley (MERV) and the Syria-Iraq border region. In late June, U.S. Secretary of Defense James Mattis stated, "Hasakah province for the first time since 2013 is now cleared of all ISIS main force element," noting the contributions of Iraqi Security Forces in those operations.61 Defense Department officials stated, "We cannot emphasize enough the contributions of the ISF in halting the movement of fighters from the battlefield and destroying targets in Syria."62

Phase two of Operation Roundup was completed in July. Coalition officials stated that the final phase of the operation will focus on clearing the last remaining pocket of IS-held territory east of the Euphrates River in Hajin, in the vicinity of Abu Kamal. Coalition officials noted that this final stage is "likely to be a challenging fight, as it is a densely populated area," and is also "one of the last holdouts of a number of foreign terrorist fighters."63 The official estimated that over 1,000 IS fighters remain in the area.

U.S. estimates on the number of IS fighters remaining in Syria and Iraq have varied. One Defense Department report released in August 2018 estimated that approximately 30,000 current and former IS personnel may remain present in areas of Syria and Iraq, including as many as 14,500 in Syria, among whom 4,000-6,000 may be in the northeast.64 In late August, Chairman of the Joint Chiefs of Staff General Dunford stated that he did not have "high confidence" in estimates attributed to Defense Department sources suggesting as many as 30,000 IS fighters remain active in Iraq and Syria.65

On August 17, U.S. Special Presidential Envoy for the Global Coalition to Counter ISIS Brett McGurk said that "the final phase" of U.S.-backed offensive operations against Islamic State-held territory in Syria was forthcoming and stated that "after that, you have to train local forces to hold the ground to make sure that the area remains stabilized so ISIS cannot return."66

In September 2018, SDF forces backed by coalition air support began ground operations for phase three of Operation Roundup.67 They are targeting the area of Hajin and surrounding villages, which U.S. military officials have described as "the last remaining territory acquired by ISIS in the coalition's area of responsibility."68 U.S. military officials estimate that between 1,500 and 2,000 IS fighters remain in the area.69

Political Negotiations

The Geneva Process

Since 2012, the Syrian government and opposition have participated in U.N.-brokered negotiations under the framework of the Geneva Communiqué. Endorsed by both the United States and Russia, the Geneva Communiqué calls for the establishment of a transitional governing body with full executive powers. According to the document, such a government "could include members of the present government and the opposition and other groups and shall be formed on the basis of mutual consent."70 The document does not discuss the future of Asad.

Subsequent negotiations have made little progress, as both sides have adopted differing interpretations of the agreement. The opposition has said that any transitional government must exclude Asad. The Syrian government maintains that Asad was reelected (by referendum) in 2014,71 and notes that the Geneva Communiqué does not explicitly require him to step down. In the Syrian government's view, a transitional government can be achieved by simply expanding the existing government to include members of the opposition. Asad has also stated that a political transition cannot occur until "terrorism" has been defeated, which his government defines broadly to include all armed opposition groups.

As part of the Geneva Process, U.N. Security Council Resolution (UNSCR) 2254, adopted in 2015, endorsed a "road map" for a political settlement in Syria, including the drafting of a new constitution and the administration of U.N.-supervised elections. In December 2017, the U.S. Deputy Representative to the United Nations stated that, "the United States remains committed to resolution 2254 (2015) as the sole legitimate blueprint for a political resolution to this conflict."72

The last round of Geneva talks, facilitated by U.N. Envoy Staffan de Mistura, closed in late January 2018. In February, the U.S. intelligence community assessed that Asad was unlikely to negotiate a political transition with the opposition:

Moscow probably cannot force President Asad to agree to a political settlement that he believes significantly weakens him, unless Moscow is willing to remove Asad by force. While Asad may engage in peace talks, he is unlikely to negotiate himself from power or offer meaningful concessions to the opposition.73

The United States has repeatedly expressed its view that Geneva should be the sole forum for a political settlement to the Syria conflict, possibly reflecting concern regarding the Russia-led Astana Process (see below). In June 2018, the U.S. Deputy Permanent Representative to the U.N. stated, "Geneva remains the sole, legitimate venue for the peaceful resolution of the Syrian conflict. Council members around this table often reiterate this message, but actions on the ground appear to suggest that some are hedging their bets and seeking to create alternatives to Geneva."74

The Astana Process

Since January 2017, peace talks hosted by Russia, Iran, and Turkey have convened in the Kazakh capital of Astana. These talks were the forum through which several "de-escalation areas" were established (see "Cease-fires" below). The United States is not a party to the Astana talks but has attended as an observer delegation. The 10th round of Astana talks was held in July 2018 in the Russian city of Sochi.

Russia has played a leading role in the Astana process, which some have described as an alternate track to the Geneva process. The United States has strongly opposed the prospect of Astana superseding Geneva. Following the release of the Joint Statement by President Trump and Russian President Putin on November 11, 2017, U.S. officials stated that,

We have started to see signs that the Russians and the regime wanted to draw the political process away from Geneva to a format that might be easier for the regime to manipulate. Today makes clear and the [Joint Statement] makes clear that 2254 and Geneva remains the exclusive platform for the political process.75

Sochi Conference. Despite the November agreement, Russia persisted in its attempts to host, alongside Iran and Turkey, a "Syrian People's Congress" in Sochi, intended to bring together Syrian government and various opposition forces to negotiate a postwar settlement. The conference concluded on January 30, but was boycotted by most Syrian opposition groups and included mainly delegates friendly to the Asad government.76 Participants agreed to form a constitutional committee comprising delegates from the Syrian government and the opposition "for drafting of a constitutional reform," in accordance with UNSCR 2254.77 The statement noted that final agreement regarding the mandate, rules of procedure, and selection criteria for delegates would be reached under the framework of the Geneva process. The United States has supported the formation of the committee under U.N. auspices, but emphasized that "the United Nations must be given a free hand to determine the composition of the committee, its scope of work, and schedule."78


Syria Southwest Cease-fire Area. In July 2017, the United States, Russia, and Jordan established a cease-fire area in southwestern Syria. The area covered parts of the Syrian provinces of Dar'a, Quneitra, and Sweida, and bordered the Golan Heights and northwestern Jordan. On November 8, 2017, the parties signed a memorandum of principles (MOP) further defining the southwest cease-fire area. The United States and Russia later issued a Joint Statement regarding the MOP and the situation in Syria. In a background briefing on the Joint Statement, State Department officials said that the MOP

… enshrines the commitment of the U.S., Russia, and Jordan to eliminate the presence of non-Syrian foreign forces. That includes Iranian forces and Iranian-backed militias like Lebanese Hizbollah as well as foreign jihadis working with Jabhat al Nusrah and other extremist groups from the southwest area.79

According to the State Department, the MOP includes a commitment to "remove Iranian-backed forces a defined distance from opposition-held territory." In July 2018, Syrian military forces recaptured the southwest cease-fire area, raising questions about the parties' continued commitment to the MOP.

Astana De-escalation Areas. As part of the Astana process, Russia, Iran, and Turkey announced in May 2017 the establishment of three "de-escalation areas" in Syria: Idlib province and its surroundings, some parts of northern Homs province, and Eastern Ghouta in the Damascus suburbs. Although the United States is not a party to the Astana Process, U.S. officials have said that they support the establishment of de-escalation areas beyond southwest Syria in principle. In 2018, the Syrian government recaptured northern Homs, Eastern Ghouta, and parts of Idlib province.

Dialogue Between Syrian Kurds and the Asad Government

In July 2018, the Syrian Democratic Council (SDC), the political wing of the U.S.-backed Syrian Democratic Forces (SDF), acknowledged that it had entered into discussions with the Syrian government. According to SDC officials, the objective of the talks was for the two sides to "work together towards a new, democratic, decentralized Syria."80 When asked whether the SDF planned to hand over areas under its control to the central government in Damascus, an SDC official stated,

One day, we want to return them to a Syrian state and not to the Syrian regime. The regime is one thing and a new Syrian state is something else. We will only return these lands to the Syrian state once we are done with setting up a new state, a new system that we will build all together through negotiations. This is what returning land to the state means.81

The Kurdish-held areas in northern Syria, comprising about a quarter of the country, are the largest remaining areas outside of Syrian government control. Asad has stated that "the only problem left in Syria is the SDF. We're going to deal with it by two options: the first one, we started now opening doors for negotiations…. This is the first option. If not, we're going to resort to liberating by force."82 Although the United States currently maintains a military presence in Kurdish areas of northern Syria, it remains unclear how long these personnel will remain. SDC officials stated, "We do not have political coordination with the U.S.; our decision to move ahead with these talks is independent, based on the high interests of our people and our nation."83

The relationship of Syrian Kurds to the central government in Damascus has fluctuated. Under an Arabization policy begun during the rule of Asad's father, many Kurds were stripped of their Syrian citizenship and lost land in "redistribution" programs that favored Arab families. However, the 2011 uprising resulted in increased autonomy for Kurdish areas. Facing manpower shortages, Syrian military forces largely withdrew from Kurdish areas of northern Syria in 2013, leaving only a small military and administrative presence in parts of Hasakah and Deir ez Zor.

Some Syrian Kurds viewed the 2011 uprising as an opportunity to push for recognition of Kurdish identity and autonomy under the framework of the broader revolution. However, the majority-Arab opposition movement was reluctant to adopt Kurdish demands for autonomy as a goal of the uprising, and called for the preservation of Syria's territorial integrity. Some groups, such as the Kurdish National Council, nevertheless elected to join the opposition movement and advocate for Kurdish interests as part of a broader platform of regime change and reform. Others (such as the PYD, whose armed militia would form the backbone of the U.S.-backed SDF), chose to focus on the goal of self-determination without an explicit commitment to regime change. As the Syria conflict developed, the PYD—and its armed wing, the YPG—defended Kurdish areas from Islamic State encroachment. However, they appeared to avoid direct confrontation with Damascus, perhaps assessing that their long-term goal for self-administration in Kurdish areas was best served by avoiding such conflict.

U.S. officials have stated that Geneva is the only legitimate framework for a political settlement to the conflict. The PYD is not a party to the Geneva talks, despite the fact that its YPG militia controls the vast majority of territory held by Kurdish forces in Syria. If PYD and YPG forces reach a separate settlement with Damascus, the Syrian government may see little to gain from continued U.N. brokered talks at Geneva.

Humanitarian Situation

As of mid-2018, the United Nations estimated that 13.1 million people in Syria were in need of humanitarian assistance, out of a total estimated population of 18 million. A third of Syria's population (6.6 million) is internally displaced, and an additional nearly 5.6 million Syrians are registered with UNHCR as refugees in nearby countries.84

The Syrian government has long opposed the provision of humanitarian assistance across Syria's border and across internal lines of conflict outside of channels under Syrian government control. Successive U.N. Security Council resolutions have nevertheless authorized the provision of such assistance. The Syrian government further seeks the prompt return of Syrian refugees from neighboring countries, while humanitarian advocates and practitioners raise concern about forced returns and the protection of returnees from political persecution and the difficult conditions prevailing in Syria. In July, a State Department spokesperson said, "We support refugees going home under these conditions—safe, voluntary, dignified returns at the time of their choosing and when it is safe to do so. I don't think the situation, as UNHCR backs up right now, allows for that at this time."85

The U.N. Secretary-General regularly reports to the Security Council on humanitarian issues and challenges in and related to Syria pursuant to Resolutions 2139 (2014), 2165 (2014), 2191 (2014), 2258 (2015), 2332 (2016), 2393 (2017) and 2401 (2018).86

U.S. Humanitarian Funding

The United States is the largest donor of humanitarian assistance to the Syria crisis, drawing from existing funding from global humanitarian accounts and some reprogrammed funding.87 As of July 2018, total U.S. humanitarian assistance for the Syria crisis since 2011 has reached nearly $8.1 billion.88

The Trump Administration's FY2019 request seeks $1.78 billion in IDA-OCO funding and $2.35 billion for MRA overseas operations—these totals include funds for responses to the Iraq and Syria crises. Both the House and Senate committee-reported versions of the FY2019 foreign operations appropriations act (H.R. 6385 and S. 3108) would provide amounts exceeding these requests on different terms.

International Humanitarian Funding

Multilateral humanitarian assistance in response to the Syria crisis includes both the Regional Refugee and Resilience Plan (3RP) and the Humanitarian Response Plan (HRP). The 3RP is designed to address the impact of the conflict on Syria's neighbors, and encompasses the Lebanon Crisis Response Plan, the Jordan Response Plan, and country chapters in Turkey, Iraq, and Egypt. It includes a refugee/humanitarian response coordinated by UNHCR and a "resilience" response (stabilization-based development assistance) led by UNDP.89

In parallel to the 3RP, the HRP for Syria is designed to address the crisis inside the country through a focus on humanitarian assistance, civilian protection, and increasing resilience and livelihood opportunities, in part by improving access to basic services. This includes the reconstruction of damaged infrastructure (water, sewage, electricity) as well as the restoration of medical and education facilities and infrastructure for the production of inputs for sectors such as agriculture.90 The 2017 3RP appeal sought $5.6 billion, and the HRP for Syria sought $3.4 billion. By the end of 2017, the two appeals had been funded at approximately 54% and 51%, respectively. The 2018 3RP appeal seeks $5.6 billion, and the 2018 HRP appeal for Syria seeks $3.5 billion.91 As of September 2018, the two 2018 appeals were funded at 42% and 43%, respectively.92

U.S. Policy

Since 2011, U.S. policy toward the unrest and conflict in Syria has attempted to pursue parallel interests and manage interconnected challenges, with varying degrees of success. Among the objectives identified by successive Administrations and by many Members in successive sessions of Congress have been

As Syria's conflict has changed over time from a situation of civil unrest and low-intensity conflict to one of nationwide military conflict involving multiple internal and external actors, the policies, approaches, and priorities of the United States and others also have changed. As of August 2018, the United States and its Syrian and regional partners have not succeeded in inducing or compelling Syrian President Bashar al Asad to leave office or secured a fundamental reorientation of Syria's political system as part of a negotiated settlement process. The United States continues to advocate for an inclusive negotiated solution, but has largely acquiesced to Asad's reassumption of political and security control. The unrestrained use of military force against civilian populated areas has been a consistent feature of the Syrian conflict since 2012, with violations of the law of armed conflict attributed by international observers to the Syrian government, several of its domestic opponents, and international actors such as Russia.

Transnational terrorist threats emanating from Syria have resulted in terrorist attacks in Europe and the Middle East, but appear to be more contained at present with the Islamic State's reign of terror over much of northeastern Syria and northwestern Iraq having come to an end. The United States remains the leading donor to ongoing international humanitarian relief efforts to assist millions of internally and externally displaced Syrians as well as the communities that struggle to support them in neighboring countries. Forceful interventions in Syria by Russia, Iran, Turkey, the United States, and Israel are creating a fundamentally different set of calculations for policymakers to consider relative to those that prevailed prior to the conflict. Similarly, the use of chemical weapons by the Syrian government in the conflict and the U.S. and international responses to that use have reshaped international norms and mechanisms for responding to chemical weapons threats.

Trump Administration Syria Policy

In 2018, the Trump Administration's Syria policy has reportedly been subject to an internal senior-level review. Some Members of Congress and other observers have expressed uncertainty about the executive branch's plans for future U.S. military activities and the specific content and scope of U.S. assistance programs. Since August, Trump Administration officials have announced some decisions apparently stemming from ongoing reassessments of U.S. policy and have made a series of policy statements outlining the contours of a revised U.S. approach.

Ambassador (ret.) James Jeffrey has been named the Secretary of State's Special Representative for Syria Engagement.93 In an interview with the Washington Post published September 6, Jeffrey stated that the Administration intends to keep U.S. military forces in Syria beyond "the end of the year" to ensure the enduring defeat of the Islamic State.94 "That means we are not in a hurry," he added. Jeffrey also implied that U.S. forces could pursue an enduring presence in part to complicate Iranian activities in Syria. With regard to diplomatic efforts to resolve the conflict, Jeffrey said that the United States no longer insists on Asad's departure from power, stating that "Asad has no future, but it's not our job to get rid of him." He further identified criteria under which Asad remaining in office might be acceptable to the U.S. government and international community, such as if Asad "doesn't threaten his neighbors," abuse his own citizens, and "doesn't allow chemical weapons or provide a platform for Iran."

On August 28, Secretary of Defense James Mattis identified conditions-based criteria when asked to describe the conditions under which U.S. forces might withdraw from Syria. Specifically, Secretary Mattis suggested at least three conditions would shape U.S. decisions about military operations: "One, we have to destroy ISIS […] We also have to have trained local troops who can take over. […] And third, we need the Geneva process, the U.N.-recognized process to start making traction towards solving this war."95

Administration officials announced in mid-August that the State Department intends to reprogram nearly $200 million in funds appropriated in FY2017 for Syria stabilization programs to priorities in other countries, and will rely on contributions from foreign partners, including a $100 million contribution from Saudi Arabia, to continue stabilization efforts in northeastern Syria.96 As of September, the Administration had begun transmitting various reprogramming notices to that effect to congressional committees of jurisdiction. The Trump Administration also has moved to end a range of U.S. nonlethal, nonhumanitarian assistance programs for opposition-held communities in northwestern Syria, including in Idlib province.97 To date, the Administration has not acted to obligate or expend funds appropriated by Congress in FY2018 foreign operations appropriations legislation for nonlethal assistance or stabilization in Syria.

President Trump has reiterated warnings to the Syrian government not to use chemical weapons and called on Syrian forces and their allies not to carry out "reckless" military operations against the large area in and near Idlib province remaining outside the Syrian government's control. On September 6, Ambassador (ret.) Jeffrey said "Any offensive is to us objectionable as a reckless escalation. You add to that, if you use chemical weapons, or create refugee flows or attack innocent civilians," and "the consequences of that are that we will shift our positions and use all of our tools to make it clear that we'll have to find ways to achieve our goals that are less reliant on the goodwill of the Russians."

Consistent with long-standing U.S. policy, a U.S. defense official has restated warnings to Syrian government forces and their allies not to attack U.S., coalition, or partner forces amid reports of a potential impending attack by pro-Asad forces near the U.S. garrison near At Tanf in southeastern Syria (Figure 1).98 Previous such incidents have resulted in U.S. force protection strikes on pro-Asad forces.

Potential Cooperation with Russia

Russia has provided support to the Asad regime since the onset of conflict in 2011. Over the summer of 2015, Moscow began a gradual buildup of personnel, combat aircraft, and military equipment, and launched its active military intervention in September 2015. Russia's military intervention on behalf of the Asad government created immediate military operational and technical challenges for U.S. forces operating in Syria. It also has generated a series of evolving strategic challenges and questions for U.S. policymakers. Key issues with regard to Russia's role and military operations in Syria include:

Military Deconfliction

In late 2015, the United States established air safety protocols with Russia to de-conflict air operations over Syria and avoid confrontations or incidents that could provoke a broader bilateral crisis. In 2017, U.S. and Russian ground forces in Syria began to operate in close proximity to one another as part of operations to defeat the Islamic State, requiring additional de-confliction measures for ground movements. This formed what U.S. military officials described as "two nodes for de-confliction with the Russians," one for the U.S. air component of the counter-IS campaign (based at Al Udeid Air Base in Qatar) and one for the ground component (at CJTF-OIR headquarters at Camp Arifjan in Kuwait).99 In 2018, Secretary Mattis referenced an additional line of communication between the Joint Staff J5 (Strategic Plans and Policy) and the Russian General Staff in Moscow.100 Secretary Mattis has also emphasized that "in regard to Syria, what we do with the Russian Federation is we deconflict our operations. We do not coordinate them."101

U.S. military officials have described de-confliction measures with Russia as generally successful. U.S.-Russian de-confliction measures were tested in February 2018, when pro-Asad fighters carried out an attack on an outpost in the eastern province of Deir ez Zor where a team of U.S. special forces was colocated with local partner forces for operations against the Islamic State. The U.S. special forces and partner ground forces repelled the attack, and U.S.-led coalition forces launched defensive airstrikes on the attacking party.102 Reports indicated that Russian military contractors (or mercenaries) were with the proregime forces and that potentially dozens were killed.103 Secretary of Defense James Mattis testified that, "The Russian high command in Syria assured us it was not their people. And my direction to the chairman was—for the force, then, was to be annihilated. And it was."104

Russian Humanitarian Proposals

At the July 2018 U.S.-Russia summit, President Putin stated his view that the two countries might cooperate on refugee return.105 U.S. officials later emphasized that any cooperation with Russia on political and humanitarian issues in Syria, including refugee return, should occur within the framework of the U.N.-brokered Geneva process.106 Reports suggest that Russian officials have circulated detailed logistical plans for facilitating the return of refugees from neighboring countries to Syria under Syrian government auspices. Efforts would include the preparation of special crossing points and camps for accommodation paired with requests for increased international contributions to reconstruction efforts. In June 2018, a UNHCR spokesperson stated, "in our view, conditions in Syria are not yet conducive for an assisted return."107

In July, General Joseph Votel, Commander, U.S. Central Command, observed when asked about working directly with Russia on refugee return that he had "not recommend[ed] that" and "would want to make sure that this isn't something that we stepped into lightly."108 The Russian Ministry of Defense criticized General Votel for, they said, "discredit[ing] the official position of his supreme commander-in-chief."109 In the weeks following the summit, U.S. officials minimized the impact of the summit on U.S. policy. Secretary Mattis stated that "there have been no policy changes."110

Russia, Israel, Iran, and Security in Southwest Syria

Reportedly, Israeli officials continue to consult with Russian counterparts about deconflicting Israeli military operations in Syria and ways to limit Iran's presence there.111 In April, Russia's ambassador to Israel said:

Russia constantly takes into account Israel's concerns and interests vis-à-vis preserving its national security. We are, of course, concerned with the state [which] the bilateral relations between Israel and Iran are in, in light of mutual threats and rejection by both countries. We must also be concerned with Iran's presence in Syria now. It may lead to a worsening of the situation and a conflagration in the entire Middle East.112

Israeli officials have communicated to Russian counterparts that they will accept Asad's control over Syria if Iran-backed forces vacate the country.113 After a meeting with Putin in July, Israeli Prime Minister Binyamin Netanyahu reiterated this position, citing a long history of stability between Israel and Syria in the Golan Heights.114 Later, as Syrian government troops consolidated their control over the area opposite the Israeli-occupied part of the Golan, Russian officials said that they could not compel Iran to leave Syria, but announced that heavy Iranian weaponry was being pulled back to at least 85 km from Israeli-controlled areas. It has been assessed by some that Russian officials view Israel's engagement with Russia as recognition that Russia rather than the United States may have more influence in Syria.115 Israel continues to insist on no Iranian intervention or entrenchment in Syria in order to prevent a "new Hezbollah front" on its northern border.116

In a press conference following a July 16 summit with President Trump, Russian President Vladimir Putin stated a desire to have the situation between Israel and Syria in the Golan return to what it had been before Syria's civil war,117 echoing an earlier statement from Israeli Defense Minister Avigdor Lieberman.118 That prewar status quo was based on a 1974 agreement in which the United Nations Disengagement Observer Force (UNDOF) took responsibility for patrolling a demilitarized area separating Israeli- and Syrian-controlled zones.119 In early August, a Russian military general staff officer announced that UNDOF peacekeepers returned to patrol the demilitarized area for the first time since a general pullback to the Israeli-controlled side in 2014.120 Russia has deployed military police near the demilitarized area on the Syrian-controlled side to prevent "provocations" until the situation stabilizes sufficiently to allow Syrian government forces to take over the Russian observation posts.121 As of mid-August, Russian military police had established four posts along the Syrian side of the disengagement zone (the Bravo line). Russian officials stated the posts could be expanded to eight.122

Syria and NDAA Prohibition on U.S.-Russia Cooperation

Section 1242 of the FY2015 NDAA (P.L. 113-291) states that none of the funds to be appropriated by the act may be used for bilateral military-to-military cooperation between the United States and Russia until the Secretary of State certifies that Russia has ceased its occupation of Ukraine and other "aggressive activities" that threaten NATO states. This prohibition has been extended in annual defense authorization legislation. Section 1231 of the FY2018 NDAA (P.L. 115-91) extended that limitation to include FY2018 funds. The FY2019 NDAA (P.L. 115-232) further extends the limitation to FY2019 funds, and adds that "Nothing in sub-section (a) shall be construed to limit bilateral military-to-military dialogue between the United States and the Russian Federation for the purpose of reducing the risk of conflict.'' Section 1232 of the FY2017 NDAA states that the Secretary of Defense may waive the limitation restricting bilateral cooperation if he determines that the waiver is in the national security interests of the United States, and submits a notification and report to the appropriate congressional committees.

Potential Confrontation with Iran

Iran's intervention in Syria on behalf of and at the invitation of President Asad has empowered a range of pro-Asad armed groups, including Lebanese Hezbollah, and has brought Iranian forces into Syria that Israel views as directly threatening its security. The United States has monitored the activities of Iran and its associated forces and at times has clashed with Iran-backed militia forces for force-protection reasons, but has not adopted a directly confrontational posture toward Iranian personnel.

In early 2018, then-Secretary of State Tillerson stated that one goal of U.S. policy in Syria was to reduce Iran's influence there. U.S. military leaders subsequently emphasized that the defeat of the Islamic State remained their "sole and single task" and that countering Iran was not yet a U.S. military objective.123 CENTCOM Commander General Votel has stated that through relationships with local partners in Iraq and Syria, U.S. military personnel could "indirectly" affect Iranian objectives in the region by helping to develop border-control forces that could challenge Iran's cross-border activities.

Since then, various Administration officials have described the Iranian presence in Syria as a potentially greater threat than the continued rule of President Asad:

Presidential Authority to Strike Syria Under U.S. Law127

Since 2011, Members of Congress and successive Administrations have debated presidential authority to conduct military operations in Syria absent a declaration of war. This has, over time, included debates regarding the potential imposition of no-fly zones over areas of the country to protect civilians, operations against various extremist groups, force protection for U.S. military personnel and partner forces inside Syria, and strikes against Syrian chemical weapons facilities and related forces. In April 2018, U.S. missile strikes targeted chemical weapons-related facilities in Syria, in response to a chemical weapons attack in the city Douma. The strikes occurred just over a year after the U.S. strike on Al Shayrat airbase in Homs province, following the sarin gas attack in Khan Sheikhoun. Describing the Administration's view of the authorities underlying the 2018 operation, Defense Secretary Mattis stated,

As our commander in chief, the president has the authority under Article II of the Constitution to use military force overseas to defend important U.S. national interests. The United States has an important national interest in averting a worsening catastrophe in Syria, and specifically deterring the use and proliferation of chemical weapons.128

Similarly, in an April 8, 2017, letter to Congress, President Trump had stated that he had acted "pursuant to my constitutional authority to conduct foreign relations and as Commander in Chief and Chief Executive" in ordering the April 6, 2017, U.S. missile strikes on Al Shayrat airbase. In the letter, President Trump says that he "acted in the vital national security and foreign policy interests of the United States," and that, "the United States will take additional action, as necessary and appropriate, to further its important national interests."129

In the past, Presidents have justified the use of military force by relying on presidential powers they assert are inherent under Article II Commander in Chief and Chief Executive authority. The executive branch has claimed that a President may use military force to defend U.S. national security interests (even when an immediate threat to the United States and its Armed Forces is not necessarily apparent) and to promote U.S. foreign policy.

In 2017 and 2018, the U.S. military used force against the Syrian government and its allies on limited occasions for force-protection purposes, including for the protection of U.S. partner forces. In an August 2017 letter to Senate Foreign Relations Committee Chairman Senator Bob Corker, the State Department asserted that "the 2001 AUMF also provides authority to use force to defend U.S., Coalition and partner forces engaged in the campaign to defeat ISIS to the extent such use of force is a necessary and appropriate measure in support of counter-ISIS operations." The letter states the Administration's view that,

The strikes taken by the United States in May and June 2017 against the Syrian Government and pro-Syrian-Government forces were limited and lawful measures to counter immediate threats to U.S. or partner forces engaged in that campaign. The United States does not seek to fight the Syrian Government or pro-Syrian-Government forces. However, the United States will not hesitate to use necessary and proportionate force to defend U.S., Coalition, or partner forces engaged in the campaign against ISIS.130

Congress has debated Syria-specific and Islamic State-focused authorization for military force proposals intermittently in recent years. In 2013, the Senate Foreign Relations Committee considered and reported a proposed authorization for the use of military force following a chemical weapons attack in the suburbs of Damascus, Syria (S.J.Res. 21, 113th Congress). The Senate did not consider the measure further.

Since U.S. military action against the Islamic State began in June 2014, starting in Iraq and then spreading to Syria, Congress also has debated the need for enactment of a new IS-specific authorization for use of military force. President Obama asserted that the campaign against the Islamic State in Iraq and Syria was authorized by both the Authorization for Use of Military Force (2001 AUMF; P.L. 107-40; claiming that the Islamic State was a successor organization of Al Qaeda and that elements of Al Qaeda were present in Syria) and Authorization for Use of Military Force Against Iraq Resolution of 2002 (2002 AUMF; P.L. 107-243; claiming authority to defend Iraq from the Islamic State threat). As noted above, Senate committees have held hearings on a proposed new AUMF (S.J.Res. 59) in 2018.

U.S. Assistance

U.S. Military Operations in Syria and U.S. Train, Advise, Assist, and Equip Efforts

U.S. Military Presence in Syria

As of December 2017, U.S. officials reported that approximately 2,000 U.S. military personnel were deployed in Syria in support of counter-IS operations.131 These include train and equip program-related activities as well as "advise and assist" operations in support of U.S. partner forces. According to 2018 oversight reporting, U.S. and coalition forces in Syria have trained more than 12,500 members of vetted Syrian opposition groups, among them more than 11,000 members of the SDF and members of Internal Security Forces and tribal forces. Four U.S. soldiers have died in northern Syria since 2016, some in non-combat related incidents.132

Military officials have identified the Special Operations Joint Task Force, Operation Inherent Resolve (SOJTF-OIR) led by Major General James Jarrard as "the primary advise, assist and accompany force in Syria, working closely with the SDF."133 SOJTF-OIR reports to the Combined Joint Task Force-Operation Inherent Resolve (CJTF-OIR), which leads the international coalition to defeat the Islamic State in Iraq and Syria.134 In September 2018, Lieutenant General Paul LaCamera assumed command of CJTF-OIR.

Evolution of the U.S. Deployment in Syria

A small contingent of 50 U.S. Special Operations Forces (SOF) initially deployed to northern Syria in October 2015 to support operations against the Islamic State. In April 2016, their numbers were increased by 250. In December 2016, the force management level (FML) for U.S. personnel in Syria increased to potentially allow the deployment of up to 500 individuals, including special operations forces trainers, advisors, and explosive ordnance disposal teams. In March 2017, roughly 300 members of the 11th Marine Expeditionary Unit deployed to Syria, providing heavy artillery support to SDF operations. An additional 100 Army Ranger forces deployed to the city of Manbij in Aleppo province. Until the revised estimate of U.S. personnel in Syria was issued in December 2017, U.S. military officials continued to reiterate that the FML for Syria remained 503, while also acknowledging that FML numbers did not include "temporary forces."

Military Authorities and Operations

As discussed above ("Presidential Authority to Strike Syria Under U.S. Law"), U.S. strike operations against the Islamic State and Al Qaeda-affiliated targets in Syria continue pursuant to the 2001 Authorization for Use of Military Force. As of December 2017, U.S. officials reported that approximately 2,000 U.S. military personnel were deployed in Syria. U.S. forces operate in Syria for train and equip program purposes as well as to advise and assist U.S. partner forces, whether or not those specific partner forces were trained and/or armed under the train and equip program. Such "advise and assist" activities may be conducted pursuant to the authorities outlined by train and equip program provisions or pursuant to other defense authorities defined in law or asserted by the executive branch. This includes military operations against IS targets conducted pursuant to the 2001 Authorization for Use of Military Force.

The Administration's FY2019 request for Syria train and equip funds envisions the requested funding supporting the procurement of weapons, vehicles, and supplies and the provision of life support and operational sustainment for a 35,000-person Internal Security Force (ISF) and 30,000-person combat force (including ISF stipends). According to the request, as of early 2018, 10,000 vetted Syrian organization members were receiving Defense Department-funded monthly stipends, although subsequent oversight reports have detailed changes to the ranks of Syrian groups receiving DOD stipend support.135

In 2014, Congress created a new authority for the Department of Defense (DOD) to train and equip select Syrians in the FY2015 National Defense Authorization Act (NDAA, Section 1209 of P.L. 113-291, as amended). This authority, as amended by subsequent legislation, enables DOD "to provide assistance, including training, equipment, supplies, stipends, construction of training and associated facilities, and sustainment, to appropriately vetted elements of the Syrian opposition and other appropriately vetted Syrian groups and individuals." Such assistance activities are authorized for select purposes, including supporting U.S. efforts to combat the Islamic State and other terrorist organizations in Syria and promoting the conditions for a negotiated settlement to Syria's civil war.

The FY2017 NDAA (P.L. 114-328) extended the authorization for the program through December 31, 2018, but the FY2018 NDAA (H.R. 2810, P.L. 115-91) did not extend it further. Instead, the FY2018 act required the President to submit a report describing U.S. strategy in Syria not later than February 1, 2018. To date, the executive branch has not submitted the required strategy report.

Congress has not appropriated funds specifically for the Syria train and equip program since the program's inception. Rather, Congress has authorized the Department of Defense to reprogram funds from global counterterrorism assistance accounts to operations and maintenance accounts to support program activities, with each reprogramming subject to the prior approval of the four congressional defense committees. As of July 2018, more than $2.2 billion has been reprogrammed or requested for the program. (Table 1 provides information about program funding and related requests.)

Table 1. Syria Train and Equip Program: Appropriations Actions and Requests

$, thousands


FY2015 Approved Transfers

FY2016 Approved Transfers

FY2017 Approved Transfers

FY2017 Requests

FY2018 Syria-Specific Request

FY2019 Syria-Specific Request



(O&M FY15)


(CTPF FY15/16)


(CTPF FY16/17)








(CTPF FY15/16)


(CTPF FY16/17)


(CTEF FY17/17)






(CTPF FY15/16)






(CTPF FY15/16)




Net Total







Combined Net Total



Source: Executive branch appropriations requests and reprogramming notifications.

Notes: Counterterrorism Partnerships Fund (CTPF). Counter-Islamic State of Iraq and Syria (ISIS) Train and Equip Fund (CTEF). The authority for the Syria Train and Equip Program requires the Department of Defense to submit prior approval notices to transfer funds into various service and department-wide Operations and Maintenance accounts for program activities. Funds listed were approved for transfer by the required congressional defense and appropriations committees during the fiscal years noted.

a. In 2016, President Obama requested $250 million for the Syria train and equip program for FY2017, and, in March 2017, the Trump Administration requested an additional $180 million in FY2017 funds for the program.

b. The Trump Administration requested $500 million for Syria train and equip program efforts as part of its FY2018 defense appropriations request for the Counter-IS Train and Equip Fund (CTEF).

c. During the period for which a continuing resolution was active for FY2017 defense funding, DOD sought and received committee approval for the reprogramming of $250 million in CTPF funds to O&M accounts. The final FY2017 defense appropriations act did not appropriate CTPF funds, and in August 2017, DOD cancelled prior approval reprogramming request 17-05 and submitted request 17-26 to reimburse O&M accounts for the cancelled funds using CTEF monies. The amount reimbursed was $168 million.

Funds appropriated for the Counter-ISIL Train and Equip Fund (CTEF) account by the FY2017 Defense Appropriations Act (Division C of P.L. 115-31) remain available to fund the program until September 30, 2018, subject to "prior approval" reprogramming procedures. President Trump requested $500 million in FY2018 defense CTEF funds for the program. The FY2018 NDAA authorizes the appropriation of that amount, and the FY2018 defense appropriations act (P.L. 115-141) appropriated the requested CTEF amount, but the act does not specify the amount for Syria-specific programs.

Other Reported U.S. Assistance

Then-Secretary of Defense Chuck Hagel said in a September 2013 hearing before the Senate Foreign Relations Committee that the Obama Administration was taking steps to provide arms to some Syrian rebels under covert action authorities.136 Several press accounts citing unnamed U.S. government sources subsequently described details of reported U.S. and partner nation efforts to that effect.137 From 2014 onward, various anti-Asad forces released videos of their operatives loading and firing what appeared to be U.S.-origin antitank weaponry in Syria.138 Asked in April 2014 about the reported shipments and use of U.S. origin weaponry by Syrian rebels, then-National Security Council spokeswoman Bernadette Meehan said, "The United States is committed to building the capacity of the moderate opposition, including through the provision of assistance to vetted members of the moderate armed opposition. As we have consistently said, we are not going to detail every single type of our assistance."139 In October 2015, unnamed U.S. officials were cited in press reports that suggested that Russia was actively targeting Syrian opposition groups that had received covert support from the United States.140 In July 2017, press reports citing unnamed U.S. officials stated that the Trump Administration had decided to end a reported program of aid to anti-Asad forces and focus instead on defeating the Islamic State via Defense Department-led train, advise, assist, and equip efforts.141

FY2019 Legislation

The FY2019 NDAA (P.L. 115-232) extends the program's authorization through the end of 2019, but also places limitations on the use of FY2019 funds for the program until certain requirements have been met. The act prohibits the obligation or expenditure of funds authorized to be appropriated for FY2019 until both (1) the President submits the report on U.S. strategy in Syria required by Section 1221 of the FY2018 NDAA (P.L. 115-91), and (2) the Secretary of Defense submits a separate report to the congressional defense committees regarding the program. The act also requires the Secretary of Defense to submit a written certification quarterly on matters including progress on stabilization as well as any human rights violations committed by U.S.-supported groups. The act continues to apply the prior approval reprogramming requirements applied to date for the use of appropriated funds.

Defense appropriations legislation for FY2019 considered in the House and Senate would have provided funding for the CTEF account on differing terms.142 Reflecting Senate concerns, the conference version of the bill would not provide some funds for Syria due to "insufficient budget documentation."

Issues for Congress

Over time, both the purposes and the content of the Train and Equip program have evolved. The Obama Administration initially proposed the program in early 2014 as a means to influence the outcome of Syria's civil war, but amended its authorization and appropriations requests to Congress later that year to include and emphasize counterterrorism objectives in the midst of the Islamic State's contemporaneous territorial gains in Syria and Iraq. After an initial iteration of the program designed to recruit, train, and equip new forces failed to produce intended results, the Obama Administration reengineered its approach in October 2015 to emphasize and focus on support of vetted existing forces actively engaged in operations against the Islamic State. This approach has defined the program's implementation since, with U.S. training and equipping efforts focusing on improving the capabilities of the Syrian Democratic Forces (SDF), along with smaller U.S. partner forces based in southeastern Syria.

During congressional consideration of proposed train and equip authorities in 2014, some Members of Congress raised questions about how the executive branch might respond in instances where U.S. personnel or partner forces in Syria came under threat. These debates reflected concern among some Members of Congress that U.S. military personnel inside Syria might come under threat from Syrian military forces or their allies, which could risk confrontation with the Syrian government and/or its state and nonstate partners—including Russia, Iran, and Hezbollah—in the event of U.S. preemption or retaliation.

Since 2015, U.S. forces in Syria have participated in military operations in forward areas where contact with various hostile forces has occurred. The Obama Administration stated its intent to defend U.S. personnel and partner forces in Syria, but did not conduct force-protection strikes against the Syrian government or its allies. During 2017 and 2018, U.S. military strikes have targeted units of regular and irregular forces aligned with the government of Syria in instances where U.S. forces have determined that those units have posed direct threats to U.S. personnel and/or to U.S. partner forces. U.S. forces also reportedly have returned fire in areas where nonstate actors who may have Turkish support have fired small arms at or near U.S. positions near the northern city of Manbij. In July 2017, the Trump Administration described a series of strikes taken to defend U.S. and partner forces in 2017 as "limited and lawful measures to counter immediate threats to U.S. or partner forces engaged" in the campaign against the Islamic State. Administration officials asserted that U.S. forces derive the authority to protect themselves and their partners from the underlying authorities the executive branch cites for the U.S. military presence in Syria.

The U.S. military expects that the Islamic State organization will be defeated as a coherent military force in Syria in the near term, and DOD officials have requested funding to reshape the content and conduct of U.S. assistance programs and parallel U.S. military operations in Syria in response. In December 2017, a DOD spokesman said that "While the nature of U.S. support to partner forces will adjust as the coalition shifts from major urban combat operations to stabilization tasks, U.S. support will not end until the enduring defeat of ISIS and will be determined by conditions on the ground."143 As noted above, DOD's FY2019 request for train and equip funding in Syria envisions the creation of U.S.-supported security forces in opposition-held areas of northern and eastern Syria with up to 65,000 members. Pending and future requests may reopen debates in Congress about the proper scope, nature, and limits of ongoing U.S. military operations and training and equipment support.

Evolution in future U.S. support could feature an increased emphasis on counterterrorism and internal security capacity building assistance for U.S. partner forces relative to past efforts to increase military capacity. Such evolution could also result in a reduction in specific types or amounts of support based in response to changing conditions. Specifically, this might entail changes in prevailing patterns of training and/or equipment provision to past partners. The FY2019 request projects more spending on sustainment of partner forces than on weapons and equipment relative to past requests. These types of changes, in turn, could have implications for the security of U.S. partner forces, and could prompt changes in their domestic political orientation, security, and attitudes toward the United States.

In particular, U.S. assistance to elements of the Syrian Democratic Forces to date has enabled SDF units to operate across large areas of northeastern Syria and deploy relatively formidable military capabilities against their Islamic State adversaries. To the extent that distinct components of the SDF, including Kurdish YPG fighters, also seek to preserve and protect the autonomy and security of Kurdish areas and support distinct political prerogatives, changes in patterns of U.S. assistance might have security and political effects. The empowerment of new groups and individuals as part of efforts to recruit, train, equip, and sustain the Internal Security Force may also have important political and security implications in local areas.

U.S. Nonlethal Assistance to Syrians and the Syrian Opposition

A broad set of bilateral U.S. sanctions on Syria existed prior to the outbreak of conflict, and some, such as those triggered by Syria's designation as a state sponsor of terrorism, initially had a limiting effect on the delivery of U.S. assistance in the country. At the executive branch's request, Congress has granted it specific authority to provide nonlethal foreign assistance in Syria for certain purposes notwithstanding other provisions of law, and the executive branch has acted to waive other restrictions imposed by law. Outside of the proscribed eligible purposes, U.S. assistance to Syria remains restricted by a series of preexisting provisions of law (including some terrorism-related sanctions provisions). Territorial gains by the Syrian military over the past year have intensified congressional concern (as seen in legislative proposals such as H.R. 4681) about whether U.S. funds could inadvertently benefit the Asad government, and have raised questions about the future of U.S. assistance inside Syria.

In August 2018, the Trump Administration announced it would reprogram nearly $200 million in FY2017 funds appropriated by Congress for cross-border stabilization programs in Syria and instead rely on contributions from foreign partners, including a $100 million contribution from Saudi Arabia, to continue stabilization efforts in northeastern Syria. As of August, the Administration had not acted to obligate or expend funds appropriated by Congress in FY2018 foreign operations appropriations legislation for nonlethal assistance and stabilization in Syria. It remains to be seen whether the Administration will do so.

Trump Administration officials have stated their view that the announced changes in U.S. stabilization funding policy will not diminish the scope of stabilization activities or U.S. leadership of stabilization efforts.144 It remains to be seen whether the changes result in arrangements in which U.S. government personnel are less directly involved in program implementation and management than they would have been if U.S.-funded programs were maintained. The Administration has reiterated its intent to prioritize the direction of stabilization assistance to areas liberated from the Islamic State over other areas where non-IS extremist groups are active or where the Syrian government and its allies have reasserted control.

Foreign Assistance Authorities and Operations

The FY2014 foreign operations appropriations act (Section 7041(i) of Division K of P.L. 113-76), as expanded and extended by the FY2015 act (Section 7041(h) of Division J of P.L. 113-235), made FY2015 and prior year ESF funding available "notwithstanding any other provision of law" for select nonlethal purposes inside Syria. The FY2016 appropriations act (Section 7041(h) of Division K of P.L. 114-113) extended this authority further, granting notwithstanding exceptions for FY2016 ESF funds as well as for FY2016 funds in the International Narcotics Control and Law Enforcement (INCLE) and Peacekeeping Operations (PKO) accounts. The Obama Administration used the INCLE and PKO accounts to support justice sector activities in opposition-held areas of Syria and to provide nonlethal assistance to select armed opposition groups. The appropriations acts for FY2017 (Section 7041(j) of Division J of P.L. 115-31) and FY2018 (Section 7041(k) of Division K of P.L. 115-141) further amended and specified the categories of assistance authorized to be provided from these accounts.

Prior to the enactment of specific notwithstanding authority by Congress, the President was required to assert emergency and contingency authorities (i.e., Sections 451 and 614 of the Foreign Assistance Act of 1961, as amended) to provide nonlethal assistance to the unarmed Syrian opposition and to communities inside Syria.145 In 2012, the Administration began to use these emergency and contingency authorities to provide food rations and medical supplies to the National Coalition of Revolutionary and Opposition Forces (SOC) and the Turkey-based Syrian Military Council (SMC).

From 2014 onward, as directed by specific provisions in appropriations bills, U.S. assistance in Syria expanded to encompass a range of smaller, local groups and actors, including municipal authorities, local councils, and nongovernmental organizations in opposition-held areas.146 Syrian recipients have used U.S. assistance to bolster governance by providing services such as emergency power, sanitation, water, and education services. Other U.S. assistance programs have supported the maintenance of public safety, rule of law, and the documentation of human rights violations.

Under authorities now in effect for funds appropriated for FY2018, congressional committees of jurisdiction are notified when the Administration intends to obligate funds from designated accounts for "non-lethal assistance for programs to address the needs of civilians affected by conflict in Syria, and for programs that seek to—147

(A) establish local governance in Syria that is representative, inclusive, and accountable;

(B) empower women through political and economic programs, and address the psychosocial needs of women and their families in Syria and neighboring countries;

(C) develop and implement political processes that are democratic, transparent, and strengthen the rule of law;

(D) further the legitimacy and viability of the Syrian opposition, including local government structures in Syria and through cross-border programs;

(E) develop and sustain civil society and independent media in Syria;

(F) promote stability and economic development in Syria;

(G) document, investigate, and prosecute human rights violations in Syria, including through transitional justice programs and support for nongovernmental organizations;

(H) expand the role of women in negotiations to end the violence and in any political transition in Syria;

(I) assist Syrian refugees whose education has been interrupted by the ongoing conflict to complete higher education requirements at universities and other academic institutions in the region, and through distance learning;

(J) assist vulnerable populations in Syria and in neighboring countries;

(K) protect and preserve the cultural identity of the people of Syria as a counterbalance to extremism, particularly those living in neighboring countries and among youth;

(L) protect and preserve cultural heritage sites in Syria, particularly those damaged and destroyed by extremists;

(M) counter extremism in Syria; and

(N) facilitate the return of displaced persons to liberated areas in Syria.

Current law requires the Secretary of State to "take all practicable steps to ensure that mechanisms are in place for monitoring, oversight, and control of such assistance inside Syria," and requires the Secretary of State to "promptly inform the appropriate congressional committees of each instance in which funds appropriated by this Act for assistance for Iraq, Libya, Somalia, and Syria, the Counterterrorism Partnership Fund, the Relief and Recovery Fund, and to counter extremism and foreign fighters abroad, have been diverted or destroyed, to include the type and amount of assistance, a description of the incident and parties involved, and an explanation of the response of the Department of State or USAID, as appropriate."

Provisions in annual appropriations acts that have defined the terms for these programs have required the executive branch to update its comprehensive interagency strategy prior to obligating funds under the authorities.148 All funds obligated pursuant to the authorities have been subject to established congressional notification procedures.

Appropriations act provisions authorizing the use of funds for select purposes in Syria notwithstanding other provisions of law have not explicitly prohibited the potential obligation or expenditure of funds in areas of Syria controlled by the Syrian government. However, the joint explanatory statement that accompanied the FY2018 appropriations act states that funds made available by the act "are made available for programs in areas not controlled by the Government of Syria." As noted above, legislation under consideration in the 115th Congress (H.R. 4681) would place restrictions on the use of some types of U.S. assistance in government-controlled areas unless certain conditions are met (see "Select Proposed Syria-Related Legislation" above).

The State Department requested more than $480 million in FY2016 and FY2017 funding to provide nonlethal support to vetted, moderate armed opposition groups, other opposition actors, and communities in opposition-held areas of Syria. The Trump Administration requested $191.5 million in Overseas Contingency Operation funding for State Department-administered programs in Syria for FY2018, including $150 million in Economic Support and Development Fund (ESDF)-OCO monies. The Administration did not request Peacekeeping Operations (PKO) funding specifically for Syria, although as noted above, the FY2018 appropriations act authorized the use of PKO funds for nonlethal assistance programs. The Administration is requesting $130 million in ESDF-OCO for stabilization efforts in nongovernment-controlled areas of Syria in FY2019, out of an overall request of $174.5 million for Syria programs. Congress appropriated additional FY2017 OCO funds in the December 2016 continuing resolution to support stabilization in areas liberated from the Islamic State, although, as discussed above, the Administration in August 2018 announced that it would repurpose some of these funds for other priorities and use foreign contributions to maintain stabilization efforts.

The FY2018 appropriations act [Section 7041(j) of Division K of P.L. 115-141] authorizes the use of $500 million from various foreign assistance accounts for a "Relief and Recovery Fund" for aid to "areas liberated from, at risk from, or under the control of, the Islamic State of Iraq and Syria, other terrorist organizations, or violent extremist organizations in the Middle East and Africa." These funds could support stabilization efforts inside Syria, and appropriations legislation currently under consideration for FY2019 would direct the use of these funds and other previously appropriated funds for stabilization activities in Syria and other countries.

FY2019 Legislation

The Senate Appropriations Committee report (S.Rept. 115-282) on the FY2019 Foreign Operations appropriations bill (S. 3108) recommends $161 million in ESF funding "for stabilization assistance" for Syria (along with NADR, INCLE, and PKO funds) and would direct that funds made available "shall continue to be made available for programs described" in the FY2018 appropriations act, as well as "for programs to build the capacity of Syrian civil society, including through core support, to address the immediate and long-term needs of the Syrian people in Syria."

The Senate committee version of the bill would not require the State Department to submit an update to the comprehensive Syria strategy required by Section 7041(i)(3) of the FY2014 State and Foreign Operations appropriations bill (P.L. 113-76). It also does not include the monitoring and oversight requirements on Syria aid found in current law. The bill also would direct that additional assistance monies in various accounts be made available for a $250 million Relief and Recovery Fund (RRF) for areas liberated or at risk from the Islamic State and other terrorist organizations, and the accompanying report contains a further direction that $100 million in funds appropriated for RRF purposes in prior acts be made available for programs in Syria.

The House Appropriations Committee-approved version of the bill would limit the use of funds in Syria to funds from the ESF account, and would remove the FY2018 direction that funds be used to strengthen Syrian civil society organizations. It would not direct the use of NADR funds for explosive ordnance removal, and the bill's provision on Syria warns against the use of U.S. assistance funds in areas of Syria controlled by the Syrian government, with the exception of humanitarian assistance. The House bill would preserve the current requirement for an update to the comprehensive strategy, as well as current monitoring and oversight requirements.

Issues for Congress

To date, congressionally enacted provisions also reflect a desire to ensure that U.S. aid programs inside Syria address specific issue areas and needs, but do not inadvertently benefit the Asad government or extremist groups active in the country.149 FY2019 foreign aid appropriations bills would direct the continued spending of U.S. assistance monies on nonlethal assistance and stabilization programs, in contrast with the Administration's announced decision to end some cross-border programs and rely on foreign contributions to continue stabilization efforts. Authorities, aid conditions, and reporting requirements for U.S. assistance and activities in Syria also have appeared to reflect congressional concerns about a perceived lack of clarity regarding successive Administrations' broader Syria strategies. As discussed above, FY2019 defense legislation seeks to condition the availability of defense funding for security programs on the delivery to Congress of mandated strategy and oversight reporting on Syria strategy and policy.

Obama and Trump Administration officials have noted that U.S. efforts to deliver and monitor security assistance and other aid inside Syria have at times been hindered by host nation administrative procedures, border closures, fighting inside Syria, and risks from extremist groups. In the past, some U.S. nonlethal assistance to armed Syrian opposition groups has fallen into the hands of unintended recipients and has led to changes in delivery and oversight mechanisms.150 Infighting among some opposition forces, the empowerment of the Islamic State in Syria, and concerns expressed by other outside actors such as Russia and Turkey have created further complications over time. Although the Islamic State has lost control of border crossings it formerly held, other anti-U.S. extremist groups control some border crossings in northwestern Syria. Current law requires the Secretary of State to monitor U.S. assistance inside Syria and to inform Congress of instances in which U.S. funds "have been diverted or destroyed."

To monitor and implement U.S. assistance programs, a U.S. Syria Transition Assistance and Response Team (START) has operated from Turkey and coordinated U.S. humanitarian and foreign assistance to northern Syria, including assistance to opposition-held areas. In Jordan, the Southern Syria Assistance Platform (SSAP) has monitored and coordinated comparable U.S. humanitarian and foreign assistance to southern and eastern Syria, including assistance to opposition-held areas. The Trump Administration also has deployed a small team of U.S. civilian assistance officials (known as START Forward) inside areas of northern Syria where DOD-trained and/or equipped local forces are in control. Some START programs have been amended and/or ended in 2018 in line with the Administration's plans to focus on stabilizing former IS-held areas to the east. The future of SSAP-managed programs in southern Syria appears uncertain, as the Syrian government and its allies are reasserting control over southwest Syria, including over areas long held by opposition groups in which U.S. programs have been active.

Looking ahead, increasingly vocal demands by the Syrian government and its international supporters for an end to cross-border assistance operations may significantly complicate U.S. assistance operations and prompt difficult decisions for U.S. policymakers. This dynamic was evident in Russian objections during late 2017 to the 12-month renewal of the U.N. Security Council mandate for cross-border and cross-line humanitarian operations (Resolution 2393), but it similarly applies to ongoing Syrian government rejections of nonhumanitarian assistance operations in opposition held areas. Administration officials have stated that U.S. personnel will remain present inside Syria to assist in the implementation of stabilization efforts in areas recaptured from the Islamic State, but their planned roles and responsibilities with regard to foreign funded stabilization programs have not been publicly described in detail.

Amid the ongoing reassertion by national authorities of political and security control over formerly opposition-held areas, past recipients of U.S. foreign assistance may become politically exposed and subject to persecution. This, in turn, may prompt renewed conflict or population displacement. If a future negotiated or imposed political solution to the Syria conflict results in a still greater reassertion of sovereignty by the Syrian government, international actors may then increase their recognition of Syrian government sovereignty. Under these circumstances or in anticipation of this outcome, Congress and the Administration may revisit fundamental questions about the authorization for, purposes and content of, and volume or terms for U.S. defense and foreign assistance programs in Syria. Ongoing debates about a continued U.S. military presence and U.S. participation in potential reconstruction efforts reflect these issues, illustrating tensions between U.S. concerns about political outcomes and the potential security and humanitarian imperatives of stabilizing conflict-torn areas.

Overview: Syria Chemical Weapons and Disarmament151

The United States, the United Nations,152 and others have assessed that the Syrian government has used chemical weapons repeatedly against opposition forces and civilians in the country. Expert teams affiliated with the U.N.-OPCW Joint Mission to Investigate Allegations of the Use of Chemical Weapons in the Syrian Arab Republic (JIM) and the OPCW Fact-Finding Mission (FFM) in Syria have investigated some of these allegations and have found evidence that in some cases confirms and in others suggests that chemical weapons and/or toxic chemicals have been used in attacks by the Syrian regime and by the Islamic State.153 Any use of chemical weapons is prohibited by the Chemical Weapons Convention, which Syria joined in September 2013.

Chemical Weapons Use

The majority of reports of chemical weapons use in Syria have consisted of chlorine use in barrel bombs in addition to the use of sarin in August 2013, April 2017, and possibly April 2018.154 The use of sarin by the Syrian military in the April 2017 and April 2013 attacks was confirmed by the United Nations, and the investigation of the April 2018 attack is underway. Reports of the use of chlorine gas as a chemical weapon in barrel bombs used by the Syrian military began to surface in April 2014 and continue.155 U.N. investigators have confirmed a few cases of the use of mustard gas by the Islamic State. The OPCW established a fact-finding mission to investigate these allegations.

The Syrian government continues to deny categorically that it has used chemical weapons or toxic chemicals, while accusing opposition forces of doing so and calling into question the methods and results of some investigations into alleged chemical attacks. The Russian Federation supports the Syrian position.

2018 Chemical Attack (Douma) and U.S. Response

On April 7, Syrian government forces are suspected to have launched a chemical attack on Douma, killing at least 40 people and injuring hundreds more.156 U.S. officials described the symptoms displayed by victims as consistent with an asphyxiation agent and "a nerve agent of some type."157 Defense Secretary Mattis stated, "We're very confident that chlorine was used. We are not ruling out sarin right now."158 The attack came within the context of broader Syrian government operations to retake the rebel enclave of eastern Ghouta, on the outskirts of Damascus (see "Syrian Government Retakes Two Astana De-escalation Areas").

On April 13 (April 14 local time), more than 100 missiles were launched into Syria from British, French, and U.S. air and naval platforms in the Red Sea, the Northern Arabian Gulf, and the Eastern Mediterranean. The strikes targeted three chemical weapons storage and research sites in Syria: the Barzeh Research and Development Center on the outskirts of Damascus and the Him Shinshar chemical weapons storage and bunker facilities in Homs province.159 Contrasting the operation with the April 2017 U.S. strikes on Al Shayrat airbase, military officials stated, "Last year the focus was on the delivery [of chemical weapons]. This time, we went—the strikes went to the very heart of the enterprise, to the research, to development, to storage."160 U.S. military officials also stated that "obviously the Syrian chemical weapons system is larger than the three targets that we addressed tonight. However, these are the targets that presented the best opportunity to minimize collateral damage, to avoid killing innocent civilians, and yet to send a very strong message."161

2017 Chemical Attack (Khan Sheikhoun) and U.S. Response

On April 4, 2017, Syrian aircraft operating in rebel-held Idlib province conducted several airstrikes using what U.S. officials assessed to be a chemical nerve agent.162 The strikes, which occurred in the town of Khan Sheikhoun, killed an estimated 80 to 100 people. The Director General of the Organization for the Prohibition of Chemical Weapons (OPCW), which conducted a fact-finding mission following the attack, stated on April 19 that four of its laboratories had "incontrovertible" evidence that victims "were exposed to Sarin or a Sarin-like substance."163 In addition, then-Secretary of State Tillerson said that the U.S. government had a "very high level of confidence" that the Syrian air force had used the nerve agent sarin in two earlier 2017 attacks—on March 25 and March 30 in neighboring Hamah province.164

On April 6, 2017, the United States fired 59 Tomahawk missiles at Al Shayrat airfield in Homs province, from which U.S. intelligence sources had concluded the Khan Sheikhoun attack was launched.165 A Defense Department statement said the U.S. strike "targeted aircraft, hardened aircraft shelters, petroleum and logistical storage, ammunition supply bunkers, air defense systems, and radars" and that "the strike was intended to deter the regime from using chemical weapons again." Secretary Mattis later stated that "around 20 aircraft were taken out" by the strike.166 The United States also imposed sanctions on 271 Syrian employees of the Scientific Studies and Research Center (SSRC), the entity responsible for managing Syria's chemical weapons program.167

2013 Chemical Weapons Attack (Ghouta)

The largest-scale use of chemical weapons in Syria to date was an August 21, 2013, nerve gas attack, which the U.S. government estimated killed more than 1,400 people.168 A U.N. investigation subsequently identified the nerve agent as sarin. The U.S. intelligence community assessed that the Syrian government had "used chemical weapons on a small scale against the opposition multiple times in the last year."169 President Obama requested congressional approval of a limited authorization for the use of military force to respond. As part of a diplomatic solution to the crisis based on a U.S.-Russian joint proposal, the Obama Administration withdrew the threat of military force and Syria agreed to give up its chemical weapons and join the Chemical Weapons Convention (CWC). U.N. Security Council Resolution 2118 (2013) further mandated that Syria give up all its chemical weapons under Chapter VII provisions of the U.N. Charter.170

Syria and the CWC: Disarmament Verification

After joining the CWC in September 2013, Syria declared that it possessed 1,308 metric tons of chemical warfare agents and precursor chemicals, including several hundred metric tons of the nerve agents sarin and VX, as well as mustard agent in ready-to-use form. The nerve agents were stored as two separate components that are combined before use, called precursor chemicals, a form that facilitated removal and destruction efforts. The international community oversaw the removal and destruction of the declared chemical weapons agents from Syria, and, as of January 4, 2016, all declared Category 1 and 2 chemicals had been neutralized.171

Verification of the destruction of Syria's chemical weapons facilities is still underway. As of June 2018, the OPCW had verified that 25 of the 27 declared chemical weapons production facilities (CWPFs) had been destroyed. One of the two remaining facilities was destroyed, and verification is underway. The OPCW is to assist Syria in destroying these facilities.172

The continued use of chemical weapons in Syria has raised questions about Syrian compliance. In addition, the OPCW has not been able to verify the completeness of the Syrian initial declaration, part of Syria's obligations after having joined the CWC. For years, the United States, the OPCW Director General, and other governments have asserted that Syria had not declared all of its chemical weapons stocks and facilities.173 The OPCW's Declaration Assessment Team (DAT) continues to investigate "gaps, inconsistencies and discrepancies" through interviews and lab analysis of samples from site visits according to OPCW Executive Council reports.

International Investigations

Since the first reports of alleged chemical weapons use during the conflict in Syria, the U.N. Secretary-General, the U.N. Security Council, and the CWC Executive Council have formed several different bodies to investigate chemical weapons use in Syria, outlined below. Of these, OPCW inspections to verify CWC compliance as well as the OPCW Fact Finding Mission are the only two currently functioning:

Earlier U.N. and OPCW investigations starting in 2013 had not been tasked with assigning responsibility for alleged attacks but were to identify whether and which type of chemical weapons were used. This changed with the JIM, which was mandated to attribute attacks. The JIM was to have access anywhere in Syria; however, the JIM's mission was complicated by the security situation on the ground.

The OPCW FFM and JIM have concluded with a high degree of confidence that chemical weapons have been used in Syria in 48 incidents from April 2014 to November 24, 2017. All incidents occurred in governorates considered by the Syrian government as outside its effective control from 2014 to present. The JIM was able to attribute the use of chemical weapons in 7 of these 48 incidents.180 The JIM concluded that the Syrian Armed Forces dropped barrel-bombs containing chlorine or a chlorine-like substance from helicopters on towns in the Idlib Governorate in three attacks: Talmenes on April 21, 2014, Qmenas on March 16, 2015, and Sarmin on March 16, 2015.181 The FFM concluded in its June 2017 report that sarin had been used as a weapon in Khan Sheikhoun, Idlib Governorate on April 4, 2017.182 The JIM concluded on October 26, 2017, a few weeks before the expiration of its mandate, that the Syrian Armed Forces used sarin-filled aerial bombs in the Khan Sheikhoun attack, and that ISIL used sulfur mustard-filled mortars in attacks in Um Housh, Aleppo Governorate on September 15 and 16, 2016.183

The Security Council extended the mandate of the JIM through November 2017 but further attempts to renew the mandate were blocked by Russia, which argues for a wider regional coverage.184 In January 2018, the French government gathered 30 countries in Paris to announce a new effort, the "International Partnership against Impunity for the Use of Chemical Weapons," to raise awareness of the issue, strengthen international action against CW use, and bolster international pressure on Syria.185 Then-U.S. Secretary of State Rex Tillerson attended.

Repeated efforts by these states to pass U.N. Security Council resolutions condemning attacks have been blocked by a Russian veto on multiple occasions.186 The latest incidence of chemical weapons use on April 7, 2018, elevated these issues again to the U.N. Security Council, where Russia defends the Syrian stance. The United States, United Kingdom, and France proposed a U.N. Security Council Resolution in support of a U.N. investigation into who was responsible for the April 7 attack, but the resolution was vetoed by Russia. Nevertheless, under the U.N. and OPCW mechanisms already in place from past Security Council resolutions, the OPCW's Fact-Finding Mission continues to investigate instances of use, including the April 2018 attack in Douma.187

In August 2011, the U.N. Human Rights Council established an Independent International Commission of Inquiry into human rights abuses and violations of international law in the Syrian conflict.188 The Commission has documented the use of prohibited chemical weapons in Syria and is specifically mandated to identify perpetrators. It is instructed "where possible, to identify those responsible with a view to ensuring that perpetrators of violations, including those that may constitute crimes against humanity, are held accountable."189 The Commission of Inquiry's 2017 report says that between March 2013 and March 2017, it documented 25 incidents of CW use in Syria, "of which 20 were perpetrated by government forces and used primarily against civilians."190


The Trump Administration has begun to announce decisions stemming from its 2018 review of U.S. policy toward Syria. The victory of pro-Asad forces in the broader conflict appears likely, and, from a U.S. perspective, that may further complicate several unresolved issues, including

In light of current trends and conditions related to these issues, Administration officials and Members of Congress may reexamine appropriate terms and conditions for U.S. investment, force deployment, and the nature of relationships with U.S. partners in and around Syria.

Consolidating Gains against the Islamic State

Combatting the Islamic State in Syria has been the top priority for U.S. policymakers since 2014, and, as of August 2018, the group has been all but eliminated as a coherent military force. U.S.-trained and -equipped partner forces control most of northeastern Syria. At present, U.S. policymakers have signaled their intention to train and equip local forces to hold and secure areas recaptured from the Islamic State, but have signaled that U.S. funds will no longer be invested at previously prevailing levels to stabilize conflict-damaged areas under U.S. partner control in Syria's northeast. Instead, the Trump Administration seeks to encourage coalition members and U.S. partners to contribute to stabilization efforts as a means of lowering the direct costs to the United States. Questions about program management, coordination, and evaluation may accompany this planned shift toward joint stabilization.

In addition, the potential reintegration of areas of Syria's east and northeast by the Asad government—whether by force or negotiation—raises other challenging policy questions.

If the resurgent Asad government adopts a confrontational posture toward U.S. forces and their local partners, renewed conflict could result and create new threats to U.S. personnel, demands on U.S. resources, and dilemmas for U.S. decisionmakers. If the Asad government adopts a relatively conciliatory approach toward U.S. partners and moves to reintegrate the northeast under its control through negotiation, it may insist on the eviction of U.S. forces and personnel or seek to absorb U.S.-trained and -equipped forces into its own ranks. In light of standing and proposed restrictions on the use of U.S. nonhumanitarian funding in Asad-controlled areas, the expansion of Syrian government control to the areas of northeastern Syria recaptured from the Islamic State could impose limits on continued U.S. involvement in stabilization activities.

Conflict in Northwestern Syria

Areas of Idlib province are the most significant zone remaining outside of government control in western Syria, and pro-Asad forces may launch military operations to reclaim areas of the province in the remaining months of 2018. Although infighting among anti-Asad groups in the province has escalated in 2018 and mutual suspicions remain between Syrian and non-Syrian fighters, extremist groups and some opposition fighters relocated to the province are expected to forcefully resist any Syrian government military campaign. Turkish forces present in some areas also may oppose or actively resist pro-Syrian government forces if hostilities erupt. The wide-scale use of military force by the Syrian government and its supporters against opposition-held areas of Idlib would likely result in significant civilian casualties and displacement and could generate renewed calls for U.S. or coalition military intervention to protect and aid civilians.

The presence in Idlib of Al Qaeda-aligned individuals remains a security concern of the United States and its allies, but the ability of U.S. and coalition forces to operate in or over Idlib may continue to be complicated by Syrian government disapproval and Russian military capabilities. If the Syrian government delays or defers action against opposition-held areas of Idlib, extremist groups hostile to the United States could enjoy some degree of continued safe haven. The Asad government also might seek to leverage the persistence of an extremist threat in Idlib to aid in its consolidation of domestic political and international diplomatic support for Asad's continued rule.

The Future of Displaced Syrians

Conflict in Syria has taken the lives of hundreds of thousands of people and has displaced millions within the country and beyond its borders. As the intensity of conflict has declined in some areas of the country, displaced Syrians have faced difficult choices about whether or how to return to their home areas amid uncertainty about security, potential political persecution, crime, economic conditions, lost or missing documentation, and prospects for recovery. The Asad government is actively encouraging internally displaced Syrians to return home and is seeking the return of Syrian refugees from neighboring countries under a Russian-designed plan. Humanitarian advocates and practitioners continue to raise concerns about the security and protection of returnees and displaced individuals in light of conditions in many areas of the country and questions about the Syrian government's approach to political reconciliation.

In addition, mechanisms and mandates that have provided for the delivery of humanitarian assistance across the Syrian border without the consent of the Syrian government could face renewed scrutiny in coming months, and the Asad government and its backers may pressure neighboring countries to forcefully return Syrian refugees that are within their jurisdictions. The United States remains the leading donor for international humanitarian efforts related to Syria, and U.S. policymakers may face a series of decisions about whether or how to continue or adapt U.S. support in light of changing conditions.


U.N. Special Envoy for Syria Staffan de Mistura has estimated that Syria's reconstruction will cost at least $250 billion.191 The Trump Administration has stated its intent not to contribute to the reconstruction of Asad-controlled Syria absent fundamental political change and to use U.S. diplomatic influence to discourage other international assistance to Asad-controlled Syria. Congress also has acted to restrict the availability of U.S. funds for assistance projects in Asad-controlled areas and has considered legislation that would further restrict such assistance through FY2023 (H.R. 4681).

In the absence of U.S. engagement, other actors such as Russia or China could conceivably provide additional assistance for reconstruction purposes, but may be unlikely to mobilize sufficient resources or adequately coordinate investments with other members of the international community to meet Syria's considerable needs. Predatory conditional assistance could also further indebt the Syrian government to these or other international actors and might strengthen strategic ties between Syria and third parties in ways inimical to U.S. interests. A lack of reconstruction, particularly of critical infrastructure, could delay the country's recovery and exacerbate the legacy effects of the conflict on the Syrian population, with negative implications for the country's security and stability.

Addressing Syria-based Threats to Neighboring Countries

Aside from terrorism threats posed by Syria-based Sunni Islamist extremists, U.S. partners and allies among Syria's neighbors perceive threats from Syria-based Iranian forces and associated militia, the reconstituted Syrian military and security services, Russia's presence, and the activities of Syria-based Kurdish armed groups. Asad's post-2015 fortunes in the conflict are largely attributable to the support of Russia and Iran. While there are some tensions reported between Syrian leaders and their foreign partners, it is difficult to foresee a scenario in the short term in which the current Syrian government would seek or be in a position to compel a fundamental change in the posture or presence of Russian or Iranian forces inside Syria. The Syrian security services, once severely degraded, have reconstituted some of their lost capabilities and may continue to grow in strength and coherence. For U.S. partners like Israel and Jordan, these conditions pose long-term strategic challenges, and any independent military or diplomatic actions on their part to address them in turn may create challenges in their relationship with the United States.

Similarly, the Turkish government expresses continuing concern about the presence and power in Syria of armed Kurdish groups, including groups partnered with the United States. Turkish military deployments inside Syria are ongoing and the prospect of confrontation between Turkish forces, U.S. forces, and their respective partners remains a real one. If the United States pursues an enduring partnership with Kurdish-led or -constituted armed groups in Syria and maintains a presence in areas under their control, related tensions in U.S.-Turkish relations may persist. If Kurdish armed groups reconcile and align with the Asad-led government, it could increase the likelihood of more pronounced confrontation between Turkey, the Syrian government, and its allies. An abrupt severance of U.S. support for Kurdish groups also could sour U.S. relations not just with Syrian Kurds, but with Kurdish populations and leaders in other regional countries.

Syria's Political Future

Since 2011, the United States has pursued a policy of seeking fundamental political change in Syria. This policy has been reflected in U.S. calls for President Asad to step aside and in U.S. support for U.N. Security Council resolutions that call for the drafting of a new constitution and the holding of free and fair elections. Asad's reelection in self-administered 2014 elections and his subsequent reconsolidation of security control in much of western Syria appear to limit the likelihood of substantive political change in line with U.S. preferences. U.N.-led negotiations over a settlement of the conflict remain open-ended, but appear unlikely to result in the meaningful incorporation of opposition figures or priorities into new governing arrangements. Alternative negotiations backed by Asad's Russian and Iranian supporters have their own logic and momentum, and place Syria's opposition groups in a political predicament. Congress and the Administration may reexamine what remaining points of leverage the United States can exercise or whether new points of leverage could be developed that might better ensure a minimally acceptable political outcome. Members of Congress and Administration officials may differ among themselves over what such an outcome might entail. Perceptions among Syrian opposition supporters of U.S. abandonment or acquiescence to an Asad victory may also have long-term diplomatic and security consequences for the United States and its partners.

Implications for Congress

As of September, Congress is considering appropriations bills for FY2019 funds, including foreign operations and defense funding for Syria programs, some of which would remain available through FY2020. As discussed above, Congress also is seeking to condition the availability for obligation of some of those funds on the Administration's provision of a new strategic plan for Syria and the delivery of oversight reporting on current Syria programs to Congress. It remains to be seen what the Administration's responses might contain and whether or how Members of Congress might react. Reaching consensus on any formal congressional counterproposal to the Administration's priorities and initiatives could be delayed until after the 116th Congress begins, and would likely be challenging in any case. In debate on the FY2019 NDAA, Congress considered but did not adopt legislative provisions that would have directed the creation of a bipartisan legislative Syria Study Group to review U.S. policy and interests in Syria.

As with Administration policy decisions, Asad's likely eventual victory in the conflict runs counter to long-stated congressional preferences and thus complicates appropriation, authorization, and sanctions decisions. Principal questions for Congress for the future may concern the extent and nature of conditions Congress places on U.S. engagement with the Asad-led government and on the expenditure of U.S. funds for programs in Asad-controlled areas.

For the foreseeable future, the essential dilemma for Members of Congress and the Administration may remain how to manage or reconcile U.S. hostility toward the Russia- and Iran-backed Syrian government with U.S. desire to stabilize areas recaptured from the Islamic State, meet the humanitarian needs of Syrian civilians, and prevent instability in Syria from chronically threatening Syria's neighbors. Even under relatively favorable circumstances, state weakness may allow extremist and terrorist groups to operate from Syria for years to come.

Observers, U.S. officials, and many Members of Congress continue to differ over which incentives and disincentives may prove most effective in influencing combatants and their supporters. Still less defined are the long-term commitments that the United States and others may be willing to make to achieve an inclusive political transition acceptable to Syrians; protect civilians; defend U.S. partners; promote accountability and reconciliation; or contribute to the rebuilding of a country significantly destroyed by years of brutal war.

Appendix A. Conflict Synopsis

2011: Protests Emerge. In March 2011, protests broke out in the southern province of Dar'a. The unrest was sparked by the arrest of a group of school children, but reflected long-standing political and socioeconomic grievances. Largely peaceful protesters called for political and economic reforms rather than the removal of the Asad government. At the same time, a small armed element was also present within some of the protests. As security forces responded with mass arrests and occasionally opened fire on demonstrators, protests became larger and spread to other towns and provinces.

The opposition movement eventually coalesced into two umbrella groups—one political, one armed—and both based primarily in exile. Political groups merged to form the Syrian National Council (SNC), although members struggled to establish trust and develop shared goals. A small number of junior military defectors formed the Free Syrian Army (FSA), which claimed leadership over the armed opposition but whose authority was generally unrecognized by local armed groups. Ongoing violence, primarily but not exclusively on the part of the Syrian government, prompted President Obama in August 2011 to call for Syrian President Asad to step aside. Meanwhile, Al Qaeda's affiliate in Iraq tasked some of its members to commence operations in Syria under the banner of a new group known as Jabhat al Nusra (aka the Nusra Front). In December 2011, the first Nusra Front suicide attacks hit government buildings in downtown Damascus.

2012: Insurgency. In 2012, the conflict became increasingly violent, as the government began to use artillery and fixed wing aircraft against opposition targets. Extremist attacks became more frequent—between November 2011 and December 2012, the Nusra Front claimed responsibility for nearly 600 attacks in Syria, ranging from more than 40 suicide attacks to small arms and improvised explosive device operations.192 In February 2012, the United States closed its embassy in Damascus, citing security concerns. Local armed groups began to seize pockets of territory around the country, primarily in rural areas. A July bombing in downtown Damascus killed several senior regime officials, including the then-Minister of Defense. Concerns about regime tactics became more acute, and President Obama in August declared that

We have been very clear to the Assad regime, but also to other players on the ground, that a red line for us is we start seeing a whole bunch of chemical weapons moving around or being utilized.... We have communicated in no uncertain terms with every player in the region that that's a red line for us and that there would be enormous consequences if we start seeing movement on the chemical weapons front or the use of chemical weapons.193

The international community also increased efforts to seek a negotiated solution to the conflict. In June, the United States and Russia signed the Geneva Communiqué, which called for the establishment of a transitional governing body with full executive powers.194 The document, which became the basis of future negotiations between the government and the opposition, did not clarify the role of Asad in any future government. Meanwhile, Syria's political opposition remained divided and in flux. In November, the SNC became part of a larger umbrella group known as the National Coalition of Syrian Revolutionary and Opposition Forces (aka the Syrian Opposition Coalition, SOC), a move which some described as an effort to dilute the influence of Islamist members.

2013: Proxy War and Chemical Weapons. In March 2013, rebels seized the city of Raqqah, which became the first provincial capital to fall out of government control. A series of other opposition victories in the area led the government to effectively concede control of Syria's rural northeast to the opposition. At the same time, the Asad government received military and intelligence support from Iran and Lebanese Hezbollah, as well as political backing from Russia. In turn, the United States, Turkey, and some European and Arab Gulf states increased their support to the Syrian opposition—each prioritizing their own interests and at times working at cross purposes.

In April, the United Kingdom and France reported to the United Nations that there was evidence that the Syrian government had used chemical weapons (CW) on multiple occasions since December 2012.195 In August, the United States attributed a large-scale CW attack on the Damascus suburb of Ghouta to the Syrian government.196 President Obama requested congressional approval of a limited authorization for the use of military force to respond.197 The following month, Russia negotiated an agreement for the Syrian government to dispose of its CW stockpiles and destroy associated facilities in exchange for staving off a U.S. military response.

2014: Caliphate and Operation Inherent Resolve (OIR). In February 2014, Al Qaeda formally disavowed the Islamic State because of the group's interference in Syria and its demands that the Nusra Front recognize IS leadership. After the Nusra Front and other opposition groups forced IS fighters from some areas of northwestern Syria, IS fighters seized vast stretches of territory in central and northeast Syria from local armed groups and in June declared the establishment of a caliphate spanning areas of both Syria and Iraq. Thousands of foreign fighters traveled to Syria and Iraq to join the Islamic State.

In August, the United States began air strikes in neighboring Iraq to stop the group's territorial advance and reduce the threat to U.S. personnel in Iraq. U.S. forces also airdropped humanitarian supplies to members of Iraq's Yazidi religious minority group trapped on Mount Sinjar. In September, the United States expanded air strikes to Syria, with the goal of preventing the Islamic State from using Syria as a base for its operations in Iraq. A subsequent air campaign to lift the IS siege on the Syrian Kurdish town of Kobane brought the United States into partnership with the Kurdish People's Protection Units (YPG). In September 2014, Congress authorized the Administration to begin a train and equip program for select Syrian forces.198 On October 17, 2014, the Defense Department established Combined Joint Task Force-Operation Inherent Resolve (CJTF-OIR) to "formalize ongoing military actions against the rising threat posed by ISIS in Iraq and Syria."

2015: Train & Equip Begins, Russia Enters the Fray. In 2015, the Syrian government faced a number of additional territorial losses. Opposition forces captured the provincial capital of Idlib in northwestern Syria and surrounding areas with the support of Al Qaeda-linked fighters. Islamic State fighters seized territory in central Homs province, and Kurdish fighters expanded their control over areas along the Turkish border. In May, the United States began training the first batch of recruits for the Syria Train and Equip Program. The program was designed to build a local force capable of fighting the Islamic State, protecting opposition-held areas, and "promoting the conditions for a negotiated settlement to end the conflict in Syria."

Over the summer of 2015, Russia began a gradual buildup of Russian personnel, combat aircraft, and military equipment inside Syria, and began air strikes in September. The following month, the United States and Russia signed a memorandum of understanding to establish a safety-of-flight protocol for aircraft operating in the same airspace. Also in October, challenges in implementation led the Administration to modify the Syria Train and Equip program to focus on equipping existing units commanded by vetted leaders. Kurdish YPG forces that had received U.S. support in operations at Kobane merged with a small number of non-Kurdish groups to form the Syrian Democratic Forces (SDF), which began to receive U.S. support.

2016: Failed Cessation of Hostilities, Regime Retakes Aleppo. In 2016, the United States sought to step up diplomatic cooperation with Russia to achieve a reduction in violence. The two countries twice attempted to implement a joint diplomatic initiative for a cessation of hostilities between progovernment and opposition forces; both initiatives were unsuccessful. In contrast, the U.S.-led campaign against the Islamic State retook significant territory from the group, severing much of the group's access to the Turkish border—a key supply and foreign fighter transit route. However, the heavy participation of Syrian Kurdish fighters in counter-IS operations triggered Turkish opposition, and in August Turkish forces crossed the Syrian border into the town of Jarabulus, in an operation described by Turkish officials as aimed at neutralizing threats posed by both the Islamic State and Kurdish fighters. Meanwhile, Syrian and Russian forces—backed by Hezbollah, foreign Shia militias, and Iranian forces—increased the intensity of attacks on rebel-held eastern Aleppo, resulting in thousands of deaths. In December 2016, the Syrian government recaptured eastern Aleppo from opposition forces, and Russia and Turkey reached agreement on a proposed cease-fire to be followed by negotiations (see "The Astana Process").

2017: U.S. Strikes Syrian Forces, Coalition-Backed Forces Retake Raqqah. On April 4, Syrian aircraft operating in rebel-held Idlib province conducted several air strikes using what U.S. officials assessed to be a chemical nerve agent.199 The strikes killed roughly 80 to 100 people in the town of Khan Sheikhoun. On April 6, the United States fired 59 Tomahawk missiles at Al Shayrat airfield in Homs province, from which U.S. intelligence sources had concluded the Khan Sheikhoun attack was launched. A Defense Department assessment stated that the U.S. strikes resulted in the damage or destruction of fuel and ammunition sites, air defense capabilities, and about 20 Syrian aircraft.200 In a series of incidents in May and June, U.S. forces carried out defensive strikes against Syrian government and allied forces deemed to be threatening U.S. forces and U.S. partners in Syria. Also in June, SDF forces began operations to retake the city of Raqqah, the self-declared capital of the Islamic State. On October 20, 2017, the SDF formally announced the recapture of the city.

Appendix B. Selected Israeli Strikes in Syria in 2018

February 10

An Iranian drone crossed from Syria into Israel, where it was shot down. Israel struck the T4 (Tiyas) military base in central Syria, from which it assessed the drone was launched. Syrian antiaircraft fire downed an Israeli F-16 participating in the operation (the plane crashed in northern Israel). Israel then struck eight Syrian and four Iranian military targets in Syria.

April 9

Israeli F-15s struck the T4 military base in Syria, reportedly targeting a newly arrived Iranian antiaircraft battery and drone hangar. Iranian press stated that the strike killed seven Iranian military personnel.

April 29

Israel struck military targets in Hamah and Aleppo provinces, reportedly killing between 16 and 26 Syrian and Iranian personnel.

May 8

Israel struck a Syrian military facility in Al Kiswah, south of Damascus. The strike killed 15 people, reportedly including 8 Iranians.

May 9-10

After an alleged Israeli strike on a target in a Syrian town on the evening of May 9, Iranian forces in Syria fired rockets into the Israeli-occupied Golan Heights in the early morning of May 10. In response, Israel struck dozens of Iranian military targets inside Syria. Israel's defense minister stated that the strikes had targeted "almost all" of Iran's military infrastructure in Syria.201 The strikes reportedly killed 23 people.

June 18

Israeli aircraft reportedly conducted a strike along Syria's border with Iraq.202 The strike targeted Iraqi militia in the area of Al Hurra, southeast of the Syrian border town of Abu Kamal. Kata'ib Hezbollah, a designated FTO, claimed that 22 of its fighters had been killed. The Iraqi government underscored that it had not authorized the affected militias to operate inside Syria.

July 11

Israel's air force struck three targets in the Syrian province of Quneitra, along the Golan Heights, after a Syrian drone infiltrated Israeli airspace.203

July 22

Israeli aircraft struck a missile production facility near Masyaf in Hamah province. Some reports indicate that Iranian and/or Hezbollah personnel were present.204

July 24

Israel shot down a Syrian Air Force aircraft near the UNDOF-patrolled disengagement zone between Syria and the Israel-occupied Golan Heights.

August 2

An Israeli air strike killed seven individuals approaching the Golan Heights disengagement zone.205 Syrian human rights organizations described those targeted as members of the IS-affiliated Jaysh Khalid Ibn al Walid.

August 4

Israeli responsibility was suspected in the death of Syrian scientist Aziz Asbar, who was killed in a car bombing in Masyaf, west of the provincial capital of Hamah. Asbar was affiliated with the Syrian Scientific Studies and Research Center (SSRC). According to media reports, Asbar was working alongside Iranian officials to develop production capability for precision-guided missiles inside Syria.206

September 4

Israel struck targets near Masyaf in Hamah province. Strikes were also reported in the coastal town of Banias.207

September 17

Israel struck military targets near Lattakia, Homs, and Hamah. A Syrian antiaircraft battery responding to the Israeli strikes downed a Russian military plane, killing 15 Russian personnel. An IDF spokesperson stated that Israeli jets were targeting "a facility of the Syrian Armed Forces from which systems to manufacture accurate and lethal weapons were about to be transferred on behalf of Iran to Hezbollah in Lebanon."208

Author Contact Information

[author name scrubbed], Coordinator, Analyst in Middle Eastern Affairs ([email address scrubbed], [phone number scrubbed])
[author name scrubbed], Specialist in Middle Eastern Affairs ([email address scrubbed], [phone number scrubbed])
[author name scrubbed], Specialist in Nonproliferation ([email address scrubbed], [phone number scrubbed])



Remarks by President Trump on the Infrastructure Initiative, March 30, 2018; Remarks by President Trump and Heads of the Baltic States in Joint Press Conference, April 3, 2018.


Worldwide Threat Assessment of the U.S. Intelligence Community, February 13, 2018.


U.S. State Department, Briefing on the Status of Syria Stabilization Assistance and Ongoing Efforts to Achieve an Enduring Defeat of ISIS, August 17, 2018.


Senate Foreign Relations Committee Hearing on U.S. Policy in Syria After ISIS, January 11, 2018.


Security Council Briefing on the Situation in Syria, Special Envoy Staffan de Mistura, November 27, 2017.


Briefing on the Status of Syria Stabilization Assistance and Ongoing Efforts to Achieve an Enduring Defeat of ISIS, David M. Satterfield, Acting Assistant Secretary, Bureau of Near Eastern Affairs and Brett McGurk, Special Presidential Envoy for the Global Coalition To Counter ISIS, August 17, 2018.


Deutsche Welle, "Russia relaunches Idlib bombing campaign," September 4, 2018.


Independent International Commission of Inquiry on the Syrian Arab Republic, "Statement by the Commission of Inquiry on Syria on the situation in Idlib," September 12, 2018.


"U.N. fears for 2.5 million in Syria's rebel-held Idlib as fighting escalates," Reuters, June 11, 2018.


Brett McGurk, Special Presidential Envoy for the Global Coalition to Counter ISIS, at the Middle East Institute, July 27, 2017.




Statement by Pentagon Spokesman Captain Jeff Davis on US strike against al-Qaida Training Camp in Syria‎, January 20, 2017.



Hassan Hassan, "Zawahiri's statements reveal plenty about Syria's fractured jihadi scene," The National, November 29, 2017; Tore Refslund Hamming, Pieter Van Ostaeyen, "The True Story of al-Qaeda's Demise and Resurgence in Syria," Lawfare, April 8, 2018.


"Armed factions join forces to counter Syrian regime gains," Al Monitor, June 6, 2018.


"11 Syrian opposition groups form new front in Idlib," Anadolu Agency, May 28, 2018.



"Syria war: Turkey 'reinforces military posts in Idlib,'" BBC News, September 13, 2018.


"The Urgency of Idlib: The Impending Regime Offensive and the Delicate Balance in Syria's Northwest," War on the Rocks, August 3, 2018.


"Turkey's Idlib Incursion and the HTS Question: Understanding the Long Game in Syria," War on the Rocks, October 31, 2017.


"Averting Disaster in Syria's Idlib Province," International Crisis Group, February 9, 2018.


"Russia says will keep bombing Syria's Idlib if need be: Interfax," Reuters, September 14, 2018.


"Large-scale operation in Syria's Idlib out of question, says Russia's chief negotiator," TASS, July 31, 2018.


"The Urgency of Idlib: The Impending Regime Offensive and the Delicate Balance in Syria's Northwest," War on the Rocks, August 3, 2018.


"Turkey to clear Idlib of militants to prevent Syrian government assault," Middle East Eye, August 1, 2018.


"Idlib takes center stage at Sochi Syria talks," Al Monitor, August 3, 2018.


"Idlib assault on hold as Russia, Turkey agree on buffer zone," Al Jazeera, September 17, 2018.


"Full text of Turkey-Russia memorandum on Idlib revealed," The National, September 19, 2018.


Widely viewed as linked to the Islamic State, Jaysh Khalid Ibn al Walid was designated as an FTO in July 2017.


"Keeping the Calm in Southern Syria," International Crisis Group Middle East Report no.187, June 21, 2018.


"Assad Regime Intentions in the Southwest De-escalation Zone," State Department Press Statement, May 25, 2018.


"Keeping the Calm in Southern Syria," International Crisis Group Middle East Report no.187, June 21, 2018.


"South Syrian rebels agree surrender deal, Assad takes crossing," Reuters, July 6, 2018.


"ISIS Bombings Shatter Quiet in Southern Syria, Killing More Than 200 People," New York Times, July 25, 2018.


"ISIS fighters offered safe passage out of Deraa in Syria," The National, July 31, 2018.


"Israel said to have hit Hezbollah convoys dozens of times," Times of Israel, August 17, 2017.


Dan Williams, "Israel says struck Iranian targets in Syria 200 times in last two years," Reuters, September 4, 2018.


An unnamed Israeli military source told Thomas Friedman of the New York Times that a strike on April 9 was the first time Israel "attacked live Iranian targets—both facilities and people." On April 17, the New York Times subsequently amended Friedman's commentary as published on April 15 to reflect the Israeli government's official position. According to Friedman, "After the story appeared, the Israeli Army's spokesman's office disputed the characterization and accuracy of the raid by my Israeli source, and emphasized that Israel maintains its policy to avoid commenting on media reports regarding the raid on the T4 airfield and other events. He would not comment further." See, Thomas Friedman, "The Real Next War in Syria: Iran vs. Israel," New York Times, April 15 and 17, 2018; Reuters, "Israel conducted April 9 strike on Syrian airbase: NYT quotes Israeli military source," April 16, 2018; Haaretz, "Israel Admits to Striking Syria: 'It Was the First Time We Attacked Live Iranian Targets,'" April 16, 2018; and, Jewish Voice, "IDF Source Credits Israel with Attack on Iranians in Syria," April 20, 2018.


Also known as Al Bukamal/Albu Kamal.


"Israel admits striking suspected Syrian nuclear reactor in 2007," BBC, March 21, 2018.


"Putin Calls Downing of Russian Plane in Syria 'Tragic,' Absolves Israel," New York Times, September 18, 2018.



Amnesty International, "'Left to die under siege': War crimes and human rights abuses in Eastern Ghouta, Syria," August 12, 2015.


United Nations High Commission for Human Rights, "Syria: Suffering of civilians in Eastern Ghouta 'an outrage' – Zeid," October 27, 2017.


Secretary Rex Tillerson, "Remarks on Russia's Responsibility for the Ongoing Use of Chemical Weapons in Syria," January 23, 2018.


Statement attributed to Ali Al-Za'tari, UN Resident and Humanitarian Coordinator in Syria, on the immediate need for a cessation of hostilities to protect and assist civilians, February 12, 2018.


Under-Secretary-General for Humanitarian Affairs and Emergency Relief Coordinator, Mark Lowcock: Statement to the Security Council on the humanitarian situation in Syria (27 March 2018).


"Rebel fighters begin leaving Syria's Douma after weeks-long military assault," Reuters, April 8, 2018.


"Rebels agree withdrawal deal for enclave near Syria's Homs," Reuters, May 2, 2018.


"Turkish army announces 'Operation Olive Branch' in Afrin," Anadolu Agency, January 20, 2018.


Department of Defense Press Briefing by Pentagon Chief Spokesperson Dana W. White and Joint Staff Director Lt. Gen. Kenneth F. McKenzie Jr. in the Pentagon Briefing Room, January 25, 2018.


"Syria 'ready to down Turkish jets attacking Kurds Afrin,'" BBC News, January 18, 2018.


"Turkish offensive in Syria leads to pause in some operations against IS: Pentagon," Reuters, March 5, 2018.


State Department Press Statement, "Concern over the situation in Afrin, Syria," March 19, 2018.


Report of the Secretary General to the U.N. Security Council S/2018/619, June 20, 2018.


Transcript, "Senior State Department Officials on the U.S.-Turkish Working Group on Syria," June 5, 2018.


"US 'deeply concerned' with situation in Syrian city taken by Turkey,", March 19, 2018.


Transcript, "Senior State Department Officials on the U.S.-Turkish Working Group on Syria," June 5, 2018.




Combined Joint Task Force-Operation Inherent Resolve Press Briefing By Col. Ryan via Teleconference from Baghdad, Iraq, September 18, 2018.


Transcript, press gaggle by Secretary Mattis, June 24, 2018.


Department of Defense Press Briefing by Col. Ryan via Teleconference, June 19, 2018.


Department of Defense Press Briefing by General Gedney via Teleconference from Baghdad, Iraq, July 31, 2018.


According to Defense Department estimates provided to Inspectors General, as of June 2018, 13,100 to 14,500 IS fighters were estimated to remain in Syria but these numbers were "in flux." Of that number, 4,000-6,000 were thought to remain in northeastern Syria, where U.S. forces and partners operate. In Iraq, Defense Department estimates suggest that 15,500 to 17,100 IS fighters remain, with some continuing to carry out attacks. See, Lead Inspector General for Operation Inherent Resolve and Operation Pacific Eagle- Philippines, Quarterly Report to the United States Congress, April 1, 2018 - June 30, 2018, released August 6, 2018.


Department Of Defense Press Briefing by Secretary Mattis and General Dunford in the Pentagon Briefing Room, August 28, 2018.


U.S. State Department, Briefing on the Status of Syria Stabilization Assistance and Ongoing Efforts to Achieve an Enduring Defeat of ISIS, August 17, 2018.


Combined Joint Task Force-Operation Inherent Resolve Press Briefing By Col. Ryan via Teleconference from Baghdad, Iraq, September 18, 2018.






Action Group for Syria, Final Communiqué, June 30, 2012,


"Syrian President Bashar al-Assad Wins Third Term," BBC, June 5, 2014.


Ambassador Michele J. Sison, U.S. Deputy Permanent Representative to the United Nations, "Explanation of Vote following the Adoption of UN Security Council Resolution 2393 on Syria," December 19, 2017.


Worldwide Threat Assessment of the U.S. Intelligence Community, February 13, 2018.


"Remarks at a UN Security Council Briefing on the Situation in Syria," Jonathan Cohen, U.S. Deputy Permanent Representative to the United Nations, June 27, 2018.


Background Briefing on the Joint Statement by the President of the United States and the President of the Russian Federation on Syria, November 11, 2017.


"Syrian Peace Talks in Russia; 1,500 Delegates, Mostly Pro-Assad," New York Times, January 30, 2018.


Final statement of the Congress of the Syrian national dialogue, Sochi, January 30, 2018.


"Remarks at a UN Security Council Briefing on the Situation in Syria," Jonathan Cohen, U.S. Deputy Permanent Representative to the United Nations, June 27, 2018.


Background Briefing on the Joint Statement by the President of the United States and the President of the Russian Federation on Syria, November 11, 2017.


"Syria's Kurds hope for 'new state and system' via Assad talks," Al Jazeera, July 28, 2018.




Transcript, Interview of Bashar al Asad by Russia Today, May 31, 2018.


"Syria's Kurds hope for 'new state and system' via Assad talks," Al Jazeera, July 28, 2018.


United Nations Office for the Coordination of Humanitarian Affairs (UNOCHA): Syria Arab Republic; UNHCR data portal: Situation Syria Regional Refugee Response.


Department of State Press Briefing, July 24, 2018.


Reports submitted by/transmitted by the Secretary-General to the Security Council available at


USAID Fact Sheet: U.S. Assistance for the People of Syria, January 26, 2018.


USAID, Syria–Complex Emergency, Fact Sheet #9, Fiscal Year (FY) 2017, July 13, 2018.


For additional details, see UNDP and UNHCR, 3RP Regional Refugee & Resilience Plan 2017 – 2018: In Response to the Syria Crisis: Regional Strategic Overview, December 5, 2016.


For additional details, see UNOCHA, 2017 Syrian Arab Republic Humanitarian Response Plan: January - December 2017.


UNOCHA Financial Tracking Service.




Joel Rayburn, a retired U.S. military officer and former Trump Administration National Security Council official has been named a State Department Special Envoy for Syria and is working with Jeffrey.


Karen DeYoung "Trump agrees to an indefinite military effort and new diplomatic push in Syria, U.S. officials say," Washington Post, September 6, 2018.


Department Of Defense Press Briefing by Secretary Mattis and General Dunford, August 28, 2018.


Acting Assistant Secretary of State for Near Eastern Affairs David Satterfield and Special Presidential Envoy for the Global Coalition To Counter ISIS Brett McGurk, Briefing on the Status of Syria Stabilization Assistance and Ongoing Efforts To Achieve an Enduring Defeat of ISIS, State Department, August 17, 2018.


"Trump administration ends aid for northwestern Syria," CBS News, May 18, 2018.


A U.S. defense official told CNN on September 6, "The United States does not seek to fight the government of Syria or any groups that may be providing it support. However, if attacked, the United States will not hesitate to use necessary and proportionate force to defend U.S., coalition or partner forces." Barbara Starr, "Russia warns U.S. of pending attack in Syrian area with U.S. troops." CNN, September 6, 2018.


Department of Defense Press Briefing by General Townsend via teleconference from Baghdad, August 31, 2017; "In Syria's Skies, Close Calls With Russian Warplanes," New York Times, December 8, 2017.


Media Availability by Secretary Mattis, July 27, 2018.


Remarks by Secretary of State Pompeo, "Press Availability With Secretary of Defense James Mattis, Australian Foreign Minister Julie Bishop, and Australian Defense Minister Marise Payne," Palo Alto, CA, July 24, 2018.


"Unprovoked attack by Syrian pro-regime forces prompts Coalition defensive strikes," CENTCOM Release # 20180208-01, February 8, 2018.


Tom O'Connor, "U.S. Coalition Kills Russians in Airstrikes Against Assad Supporters in Syria, Reports Say," Newsweek, February 12, 2018; Thomas Gibbons-Neff, "How a 4-Hour Battle Between Russian Mercenaries and U.S. Commandos Unfolded in Syria," New York Times, May 24, 2018.


Secretary Mattis before the Senate Armed Services Committee, April 26, 2018.


The White House, "Remarks by President Trump and President Putin of the Russian Federation in Joint Press Conference," July 16, 2018.


Press Gaggle at the Pentagon with Secretary of Defense Mattis, July 27, 2018; Secretary of State Mike Pompeo before the Senate Foreign Relations Committee, July 25, 2018.


"Lebanon blocks UNHCR residency permits over Syria refugee spat," France24, June 8, 2018.


Luis Martinez, "US Commander in Middle East Hesitant To Cooperate With Russians in Syria on Refugees," ABC News, July 22, 2018.


Nancy A. Youseff, "Russia Says U.S. General's Remarks Discredited Trump's Position," Wall Street Journal, July 24, 2018.


Media Availability by Secretary Mattis, July 27, 2018.


"Israel rejects Russian offer to keep Iranian forces 100 km from Golan: official," Reuters, July 23, 2018; Itamar Eichner, et al., "Russian SC chief meets Israeli, Iranian counterparts," Ynetnews, April 25, 2018.


Eichner, et al., op. cit.


See, e.g., Jacob Nagel, "Iran, Syria, and Israel's Red Line," Real Clear Defense, June 18, 2018.


Noa Landau, "Netanyahu: Israel Has No Problem with Assad, but Cease-fire Agreements Must Be Upheld," Ha'aretz, July 12, 2018.


Damien Sharkov, "Why Is Israel's Benjamin Netanyahu Warming to Russia's Vladimir Putin?" Newsweek, June 7, 2016.


Polina Nikolskaya and Dan Williams, "Russia says Iranian forces pulled back from Golan in Syria; Israel unsatisfied," Reuters, August 1, 2018.


White House, Remarks by President Trump and President Putin of the Russian Federation in Joint Press Conference, Helsinki, Finland, July 16, 2018.


"Liberman vows 'strong response' if Syrian military enters Golan DMZ," Times of Israel, July 9, 2018.


UNDOF Fact Sheet, available at


"Russia says UN peacekeepers patrol Israel-Syria border for first time in years," Times of Israel, August 2, 2018. The 2014 pullback occurred after clashes had intensified in the area between Syrian government troops and various opposition forces, and had led to the temporary abduction of peacekeepers from Fiji and the Philippines. Louis Charbonneau, "U.N. Golan peacekeepers pull back from Syrian positions amid clashes," Reuters, September 15, 2014.


"Russia says UN peacekeepers patrol Israel-Syria border for first time in years," op. cit.


"Russian military police deploys four posts on Golan heights," TASS, August 14, 2018.


Gen. Joseph Votel before the House Armed Services Committee, February 27, 2018.


Secretary of State Mike Pompeo before the Senate Appropriations Subcommittee on State, Foreign Operations and Related Programs, June 27, 2018.


Full transcript: "Face the Nation" on July 1, 2018, CBS News, July 1, 2018.


Department Of Defense Press Briefing by General Joseph Votel via teleconference from Tampa, Florida, on Operations in the Central Command Area of Responsibility, July 19, 2018.


Prepared by Matthew Weed, Specialist in Foreign Policy Legislation.


Statement by Secretary James N. Mattis on Syria, Department of Defense Press Release No: NR-113-18.


On April 6, the President said he ordered the strikes to protect the "vital national security interest of the United States to prevent and deter the spread and use of deadly chemical weapons." The April 8 letter expands upon this explanation. The letter says the strikes were intended "to degrade the Syrian military's ability to conduct further chemical weapons attacks and to dissuade the Syrian regime from using or proliferating chemical weapons, thereby promoting the stability of the region and averting a worsening of the region's current humanitarian catastrophe."


Letter to Senator Bob Corker from Deputy Assistant Secretary of State for Regional, Global and Functional Affairs Charles Faulkner, Bureau of Legislative Affairs, August 2, 2017.


"Pentagon Announces Troop Levels in Iraq, Syria," DoD News, December 6, 2017.


DoD Press Release No: NR-420-16, November 25, 2016; DoD Press Release No: NR-116-17, March 30, 2017; DoD Press Release No: NR-197-17, May 27, 2017; DoD Press Release No.: NR-093-18, March 31, 2018.


Department of Defense Press Briefing by General Jarrard via teleconference from Baghdad, Iraq, October 31, 2017.


See for an organization chart.


See Lead Inspector General for Operation Inherent Resolve and Operation Pacific Eagle- Philippines, Quarterly Report to the United States Congress, April 1, 2018 - June 30, 2018, released August 6, 2018.


Secretary Hagel said, "it was June of this year that the president made the decision to support lethal assistance to the opposition. As you all know, we have been very supportive with hundreds of millions of dollars of nonlethal assistance. The vetting process that Secretary Kerry noted has been significant, but—I'll ask General Dempsey if he wants to add anything—but we, the Department of Defense, have not been directly involved in this. This is, as you know, a covert action. And, as Secretary Kerry noted, probably to [go] into much more detail would—would require a closed or classified hearing."


Adam Entous, Julian E. Barnes and Siobhan Gorman, "U.S. Begins Shipping Arms for Syrian Rebels," Wall Street Journal, June 26, 2013; Greg Miller, "CIA ramping up covert training program for moderate Syrian rebels," Washington Post, October 2, 2013; Greg Miller and Karen DeYoung, "Secret CIA effort in Syria faces large funding cut," Washington Post, June 12, 2015.


See Harakat Hazm YouTube Channel, April 15, 2014, at


Tom Bowman and Alice Fordham, "CIA Is Quietly Ramping Up Aid To Syrian Rebels, Sources Say," National Public Radio (Online), April 23, 2014.


"U.S. Sees Russian Drive Against CIA-Backed Rebels in Syria," Wall Street Journal, October 5, 2015.


"Trump ends covert CIA program to arm anti-Assad rebels in Syria, a move sought by Moscow," Washington Post, July 19, 2017.


The House bill (H.R. 6157) would provide the Administration's requested amount for the overall account ($1.4 billion) on terms similar to prior-year appropriations. The Senate-reported bill (S. 3159) would appropriate $994 million for the account, based on a recommended rescission of $250 million for border security programs fundable through other accounts and some monies requested for Iraq and Syria due to "insufficient budget documentation." Specifically, the Senate reported version would not appropriate $72 million requested for Syria to purchase non-NATO standard weapons for U.S. partner forces.


Pentagon Spokesman Eric Pahon, quoted in Ryan Browne, Barbara Starr and Jamie Crawford, "Pentagon: US committed to Syria until ISIS areas stabilized," CNN, December 5, 2017.


U.S. State Department, Briefing on the Status of Syria Stabilization Assistance and Ongoing Efforts to Achieve an Enduring Defeat of ISIS, August 17, 2018.


Prior to the enactment of the expanded congressional authorization in 2013, U.S. assistance had been provided to select unarmed opposition groups and opposition-held communities on a periodic basis from May 2012 onward.


In August 2015, the State Department reported that "Non-lethal assistance is being provided to a range of civilian opposition groups, including local councils, civil society organizations, and SOC-affiliated entities to bolster their institutional capacity, create linkages among opposition groups inside and outside Syria, and help counter violent extremism. These efforts enable the delivery of basic goods and essential services to liberated communities as they step in to fill voids in local governance. In addition to civil administration training programs, we have provided opposition groups with a wide array of critical equipment, including generators, ambulances, cranes, dump trucks, fire trucks, water storage units, search and rescue equipment, educational kits for schools, winterization materials, and commodity baskets for needy families in the local community." Office of the State Department Spokesperson, "Syrian Crisis: U.S. Efforts and Assistance," August 7, 2015.


Per Section 7041(k) of Division K of P.L. 115-141, the FY2018 Consolidated Appropriations Act.


That strategy must include a "mission statement, achievable objectives and timelines, and a description of inter-agency and donor coordination and implementation of such strategy." The strategy, which may be classified, must also include "a description of oversight and vetting procedures to prevent the misuse of funds."


For example, the Senate Appropriations Committee report (S.Rept. 115-282) on the FY2019 Foreign Operations appropriations bill (S. 3108) states that, "the Committee remains concerned with the absence of a coherent and comprehensive strategy for stabilization of areas liberated from ISIS in Iraq and Syria."


Opposition infighting in late 2013 led to the capture of some nonlethal U.S. assistance by Islamist groups. U.S. officials subsequently revisited some delivery and monitoring mechanisms and worked to improve the reliability and security of delivery channels. Dasha Afanasieva and Humeyra Pamuk, "U.S., Britain suspend aid to north Syria after Islamists seize weapons store," Reuters, December 11, 2013.


Prepared by Mary Beth Nikitin, Specialist in Nonproliferation. See also CRS Report R43612, The Islamic State and U.S. Policy, by [author name scrubbed] and [author name scrubbed].


The U.N. Mission to investigate Allegations of the Use of Chemical Weapons in the Syrian Arab Republic released its report on September 16, 2013, concluding that surface-to-surface rockets containing the chemical weapons nerve agent sarin were used in the Ghouta area of Damascus against civilians on a "relatively large scale." The 2013 U.N. investigative mission was not tasked with assigning culpability for the attacks.


Find full reports at "The Fact Finding Mission (FFM)," OPCW,


UN Commission of Inquiry Info Graphic: Chemical Weapons Attacks Documented by the U.N. Commission of Inquiry on the Syrian Arab Republic, as of September 6, 2017; Arms Control Association, "Timeline of Chemical Weapons Attacks in Syria: 2012-2018," ACA Fact Sheet, 2018.


The use of chlorine as a weapon is banned under the Chemical Weapons Convention.


"Dozens Suffocate in Syria as Government Is Accused of Chemical Attack," New York Times, April 8, 2018.


"Douma symptoms consistent with nerve agent: U.S. State Department," Reuters, April 9, 2018.


Press briefing by Secretary of Defense Jim Mattis; Joint Chiefs of Staff Chairman General Joseph F. Dunford; Pentagon Chief Spokesperson Dana W. White, April 13, 2018.


Department of Defense Press Briefing by Pentagon Chief Spokesperson Dana W. White and Joint Staff Director Lt. Gen. Kenneth F. McKenzie Jr. in the Pentagon Briefing Room, April 14, 2018.






President Trump Statement on Syria, April 6, 2016; and, Statement from Pentagon Spokesman Capt. Jeff Davis on U.S. strike in Syria, Release No: NR-126-17, April 6, 2017.


"OPCW Director-General Shares Incontrovertible Laboratory Results Concluding Exposure to Sarin," OPCW Press Release, April 19, 2017.


Secretary of State Rex W. Tillerson, "Remarks With National Security Advisor H.R. McMaster," April 6, 2017.




Press Conference by Secretary Mattis and Gen. Votel in the Pentagon Briefing Room, April 11, 2017.


"Treasury Sanctions 271 Syrian Scientific Studies and Research Center Staff in Response to Sarin Attack on Khan Sheikhoun," April 24, 2017.


White House Office of the Press Secretary, Government Assessment of the Syrian Government's Use of Chemical Weapons on August 21, 2013, August 30, 2013.




Chapter VII of the U.N. Charter authorizes the use of punitive measures such as sanctions or military force.


Organization for the Prohibition of Chemical Weapons, "Destruction of Syrian Chemical Weapons Completed," press release, January 4, 2016.


Organization for the Prohibition of Chemical Weapons, "Note by the Director-General: Progress in the Elimination of the Syrian Chemical Weapons Programme," EC-88/GD.16, June 22, 2018.


Joint News Conference with Secretary Mattis and Minister of Defense Lieberman in Tel Aviv, Israel, Department of Defense News Transcript, April 21, 2017; Julian E. Barnes and Maria Abi-Habib, "Syrian Attack Defies 2013 Chemical-Weapons Deal," Wall Street Journal, April 6, 2017.


"Secretary-General's Press Encounter on Syrian Government Request," March 21, 2013.



OPCW Reports on the Elimination of Chemical Weapons in Syria can be found here:


"The Fact Finding Mission (FFM)," OPCW,


The decision calls upon the OPCW make arrangements "to identify the perpetrators of the use of chemical weapons in the Syrian Arab Republic by identifying and reporting on all information potentially relevant to the origin of those chemical weapons in those instances in which the OPCW Fact-Finding Mission determines or has determined that use or likely use occurred, and cases for which the OPCW-UN Joint Investigative Mechanism has not issued a report."


Resolution 2235 required that the U.N. Secretary-General, in coordination with the OPCW Director-General, submit within 20 days recommendations for its approval on the establishment of a Joint Investigative Mechanism "to identify to the greatest extent feasible individuals, entities, groups, or governments who were perpetrators, organisers [sic], sponsors or otherwise involved in the use of chemicals as weapons, including chlorine or any other toxic chemical, in the Syrian Arab Republic where the OPCW FFM determines or has determined that a specific incident in the Syrian Arab Republic involved or likely involved the use of chemicals as weapons, including chlorine or any other toxic chemical…."


In addition to these cases, the FFM and JIM have reported their recording through open sources of at least 138 other incidents involving the use of chemicals as weapons in Syria since April 2014.


U.N. Secretary-General Ban Ki-Moon, "Third Report of the Organization for the Prohibition of Chemical Weapons-United Nations Joint Investigative Mechanism," S/2016/738, August 24, 2016. "Report of the Organization for the Prohibition of Chemical Weapons-United Nations Joint Investigative Mechanism," OPCW, S/2016/888, October 21, 2016.


"Report of the Organization for the Prohibition of Chemical Weapons-United Nations Joint Investigative Mechanism," OPCW, S/1510/2017, June 29, 2017.


U.N. Secretary-General António Guterres, "Sixth Report of the Organization for the Prohibition of Chemical Weapons-United Nations Joint Investigative Mechanism," S/2017/552, June 28, 2017. U.N. Secretary-General António Guterres, "Letter Dated 26 October 2017 from the Secretary-General Addressed to the President of the Security Council," S/2017/904, October 26, 2017, Annex I.


"Syria: Renewal of the UN-OPCW Joint Investigative Mechanism," What's In Blue, November 17, 2016.


"Launch of the International Partnership against Impunity for the Use of Chemical Weapons," French Foreign Ministry, January 23, 2018.


"Syria Draft Resolution Imposing Sanctions Regarding the Use and Production of Chemical Weapons," What's In Blue, February 25, 2017.


"OPCW Will Deploy Fact-Finding Mission to Syria," OPCW Press Release, April 10, 2018.


The Human Rights Council is the primary intergovernmental U.N. body charged with addressing human rights situations worldwide. The United States is currently a Council member.

189.; see also


Report of the Independent International Commission of Inquiry on the Syrian Arab Republic, September 6, 2017.


Security Council Briefing on the Situation in Syria, Special Envoy Staffan de Mistura, November 27, 2017.


"Terrorist Designations of the al-Nusrah Front as an Alias for al-Qa'ida in Iraq," Press Statement by State Department Spokesperson Victoria Nuland, December 11, 2012.


President Barack Obama, Remarks by the President to the White House Press Corps, August 20, 2012.


Action Group for Syria, Final Communiqué, June 30, 2012.


Letter dated 22 March 2013 from the Secretary-General addressed to the President of the Security Council, U.N. Document S/2013/184, March 22, 2013.


The White House, Government Assessment of the Syrian Government's Use of Chemical Weapons on August 21, 2013, August 30, 2013. United Nations investigations confirmed that a chemical attack took place but its September and December 2013 reports did not address attribution. See U.N. Document A/67/997–S/2013/553, Report of the United Nations Mission to Investigate Allegations of the Use of Chemical Weapons in the Syrian Arab Republic on the alleged use of chemical weapons in the Ghouta area of Damascus on 21 August 2013, September 16, 2013; and, United Nations Mission to Investigate Allegations of the Use of Chemical Weapons in the Syrian Arab Republic, Final Report, December 2013.


President Barack Obama, Remarks by the President Before Meeting with Members of Congress on the Situation in Syria, September 3, 2013.


The FY2015 Continuing Resolution (P.L. 113-164, "the FY2015 CR") contained temporary authorization for the training and equipping of vetted Syrians that differed from the Administration's requests and expired on December 11, 2014. The FY2015 NDAA (Sections 1209, 1510, and 1534 of Division A of P.L. 113-291) and the Consolidated and Further Continuing Appropriations Act, 2015 ("Counterterrorism Partnership Fund" and Section 9016 of P.L. 113-235) provided further authority and funding guidance for the program.


President Trump Statement on Syria, April 6, 2017; and, Statement from Pentagon Spokesman Capt. Jeff Davis on U.S. strike in Syria, Release No: NR-126-17, April 6, 2017.


Statement by Secretary of Defense Jim Mattis on the U.S. Military Response to the Syrian Government's Use of Chemical Weapons, April 10, 2017; Press Conference by Secretary Mattis and Gen. Votel in the Pentagon Briefing Room, April 11, 2017.


"Israel Struck 'Almost All of the Iranian Infrastructure in Syria,' Defense Chief Says," Haaretz, May 10, 2018.


"Israel behind airstrike in Syria, US official says," CNN, June 18, 2018.


"Israel Strikes Three Syrian Army Positions in Response to Drone Infiltration," Haaretz, July 12, 2018.


"Israeli jets said to strike Iranian-run missile production facility in Syria," The Times of Israel, July 22, 2018.


"Israel kills seven militants in overnight strike on Syrian Golan: Israeli radio," Reuters, August 2, 2018.


"A Top Syrian Scientist Is Killed, and Fingers Point at Israel," New York Times, August 6, 2018.


"Israeli Satellite Images Reveal Damage at Site of Airstrike on 'Iranian Targets,'" Haaretz, September 5, 2018.