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 MEMORANDUM 
October 16, 2019 
 
Subject: 
Syria: Turkish Incursion and Conflict Status 
From: 
Carla E. Humud, Analyst in Middle Eastern Affairs,
 chumud@crs.loc.gov, 7-7314 
Christopher M. Blanchard, Specialist in Middle Eastern Affairs
, cblanchard@crs.loc.gov, 
7-0428 
Clayton Thomas, Analyst in Middle Eastern Affairs,
 cbthomas@crs.loc.gov, 7-2719 
Jim Zanotti, Specialist in Middle Eastern Affairs
, jzanotti@crs.loc.gov, 7-1441 
This memorandum was prepared to enable distribution to more than one congressional office. 
 
 
Overview 
A series of Administration statements and moves in October 2019 appear to have significantly altered the 
U.S. approach to the Syria conflict. After an October 6 phone call with Turkish President Erdogan, 
President Trump announced an imminent Turkish operation in northern Syria and stated that U.S. forces 
would leave the area. The Turkish-led operation, dubbed Operation Peace Spring, was launched on 
October 9, triggering an escalation of conflict between Turkish and Kurdish forces, and significant 
civilian displacement. 
On October 13, President Trump directed the full withdrawal of the approximately 1,000 remaining U.S. 
troops in northeast Syria (
Figure 1).
1 In a statement posted to Twitter on October 14, he stated that U.S. 
troops leaving Syria would redeploy in the region to “monitor the situation.”
2 Defense Department 
officials said that most U.S. personnel currently based in Syria would move to Iraq by the end of October; 
roughly 125 U.S. personnel would remain at the At Tanf garrison in southeastern Syria (
Figure 2).
3 The 
U.S. withdrawal followed the launch of military operations against U.S. partners in the Syrian Democratic 
Forces (SDF) by the Turkish military and allied Syrian militia groups under the rubric of Turkey’s 
Operation Peace Spring (OPS). The SDF, seeking protection from Turkish operations, invited Syrian 
military forces, backed by Russian personnel, to reenter SDF-held areas of northeastern Syria. 
Prior to the withdrawal announcement, Administration officials described U.S. policy in Syria as seeking 
1) to prevent the resurgence of the Islamic State by training local partner forces—the SDF and other 
vetted Syrian opposition groups, 2) a political solution to the Syria conflict based on U.N. Security 
Council Resolution 2254, which calls for the drafting of a new constitution and U.N.-supervised 
elections, and 3) the withdrawal of all Iranian-commanded forces. Unnamed U.S. officials have stated that 
                                                 
1 “U.S. Military to Withdraw From Northern Syria,” 
Wall Street Journal, October 13, 2019.  
2 Statement from President Donald J. Trump Regarding Turkey’s Actions in Northeast Syria, October 14, 2019.  
3 “U.S. Military to Withdraw From Northern Syria,” 
Wall Street Journal, October 13, 2019. 
 
 
  
 
Congressional Research Service 
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U.S. objectives remain unchanged in the wake of the President’s decision. Nevertheless, the withdrawal 
of U.S. military forces from northeastern Syria and corresponding military moves by Turkey, the Syrian 
government, and Russia fundamentally change the context in which U.S. objectives are to be pursued.  
Relevant issues and questions for Congress may include: 
•  Security conditions in northeastern Syria appear to be deteriorating in some areas and reports 
suggest that Islamic State supporters are attempting to exploit the fluidity on the ground. What 
immediate effects is the withdrawal having on security conditions in northeastern Syria? What 
evidence is there that the Islamic State group has benefitted from resulting developments to date? 
What implications does the U.S. withdrawal have for the security of U.S. partners in Jordan, Iraq, 
and Israel, and for U.S. relations with those partners? 
•  It appears likely that the ability of U.S. military forces to conduct operations in large areas of 
eastern Syria will now be constrained and contested by the advance of Syrian and Russian forces 
into areas formerly controlled by U.S. allies. This suggests that counterterrorism and security 
responsibilities will shift more wholly to non-U.S. forces. State Department and USAID 
personnel will most likely be unable to redeploy in the area, curtailing stabilization activities. 
How capable are Syrian and Russian forces of extending security control over northeastern Syria 
and preventing the resurgence of the Islamic State group? To what extent do they prioritize the 
counter-Islamic State mission? What posture should the United States take with regard to counter-
IS efforts and stabilization by Turkey, Syria, and Russia? What are the prospects for military 
confrontation between Turkey and the Syrian government, backed by Russia? 
•  Political elements of the SDF forces had created a de facto autonomous political structure in 
northeastern Syria that is now being reconciled with and/or subsumed under the control of the 
Asad government in Damascus. How might any reassertion of political and security control by 
the Syrian government over northeastern Syria affect the overall balance of power in Syria, and 
prospects for a political solution to the Syrian conflict? How might the Asad government and its 
backers change their approach to negotiations? Why, and with what implications for the United 
States? What relative effect does the U.S. withdrawal have on U.S. influence over future 
negotiations? Why? 
•  U.S. forces in northeastern Syria were not directly contesting the activities of Iran-aligned 
elements of the Syrian and Iraqi security forces in the area, but were in a position to monitor 
them. U.S. forces regularly operated along routes connecting the two countries. How might the 
withdrawal affect patterns of Iranian weapons shipments via Syria? How if at all does the 
announced U.S. withdrawal affect U.S. options for monitoring and interdicting Iranian weapons 
shipments? Does the U.S. withdrawal increase or decrease the likelihood of the withdrawal from 
Syria of Iranian forces? 
•  The Administration’s FY2020 requests for defense and foreign aid appropriations presumed 
continued counterterrorism, train and equip, and humanitarian operations in Syria. In addition, 
Congress has been debating proposals that would have extended and amended related authorities 
and made additional funding available to continue U.S. efforts. What revised defense and foreign 
assistance needs, if any, has the Administration identified in connection with the U.S. 
withdrawal? How, if at all, should Congress increase, decrease, or reallocate defense, 
humanitarian, and stabilization resources for FY2020 in light of the withdrawal, and the 
recalibration of the U.S. relationship with the SDF? What, if any, new or revised oversight 
mechanisms should Congress employ? 
  
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Recent Developments 
White House Announces Limited Troop Withdrawal 
Following an October 6 call between President Donald Trump and Erdogan, the White House
 announced 
that Turkey would “soon be moving forward with its long-planned operation into Northern Syria,” and 
that U.S. forces would “no longer be in the immediate area.”
4 Some Members of Congress the
n argued 
that a “precipitous withdrawal” of U.S. forces would benefit Russia, Iran, the Islamic State, and the 
Syrian regime.
5 State Department a
nd Pentagon officials subsequently emphasized that roughly 50 U.S. 
Special Forces personnel had been withdrawn from two outposts to 
“more secure areas,” and that the 
move did not signal a pullout of U.S. troops from Syria.
6 On October 8, President Trum
p tweeted, “We 
may be in the process of leaving Syria, but in no way have we Abandoned the Kurds.” Trum
p warned that 
if Turkey took any unspecified steps that he considered “off-limits,” he would “totally destroy and 
obliterate” Turkey’s economy, while also
 inviting Erdogan to Washington in mid-November. Following 
the start of Operation Peace Spring, President Trump
 stated, “The United States does not endorse this 
attack and has made it clear to Turkey that this operation is a bad idea.”  
Turkey Begins Operation Peace Spring 
On October 9, Turkish President Recep Tayyip Erdoga
n announced the start of “Operation Peace Spring,” 
which he stated would target both Kurdish and Islamic State (IS, aka ISIL/ISIS) fighters—both of which 
Turkey classifies as terrorist groups—in northern Syria. Turkey then launched an air and ground assault 
against Kurdish forces. Turkey’s foreign minister
 stated that Turkish forces planned to go no further than 
about 19 miles into Syrian territory, a distance he said was necessary to prevent Kurdish fighters from 
firing into Turkey.
7  He also stated that Turkey eventually planned to occupy a corridor along the border. 
The commander of the Kurdish-led Syrian Democratic Forces (SDF)
 stated that the SDF would resist, and 
fighting has
 escalated. While this is the third discrete military operation conducted by Turkey since 2016, 
prior Turkish incursions into Syrian territory have, according to public accounts, thus far largely avoided 
conflict with the specific elements of the SDF that U.S. forces have partnered with in the campaign 
against the Islamic State.   
As of October 11, the Turkish incursion had impacted approximately 125 kilometers of the roughly 440 
kilometer Syria-Turkey border, according to U.S. military officials.
8 U.S. officials stated that the Turkish 
incursion involved airstrikes (fixed wing and UAV), artillery strikes, and direct fire from tanks on the 
Turkish side of the border. U.S. military officials described Turkish ground force elements that have 
crossed into northern Syria as “relatively limited,” consisting of “hundreds” of Turkish light infantry 
forces operating in conjunction with approximately 1,000 Syrian opposition forces (Syrian National 
Army, formerly known as the Free Syrian Army). Turkish officials stated that they had advanced 19-22 
miles into Syria, and taken control of parts of the M4 highway, and, on Tuesday said they controlled 
approximately 1,000 square kilometers, or about 386 square miles.
9 (See 
Figure 1). 
                                                 
4 White House Statement from the Press Secretary, October 6, 2019.  
5 Press Release, “McConnell Statement on Turkey and U.S. Partners in Syria,” October 7, 2019.  
6 “Trump Whipsaws on Turkey as Threat Follows Green Light on Syria,” Bloomberg, October 7, 2019; Department of Defense 
Press Release, “Statement Attributable to Assistant to the Secretary of Defense for Public Affairs Mr. Jonathan Hoffman,” 
October 7, 2019.  
7 “Turkish Forces Escalate Campaign in Syria Against Kurdish-Led Militia,” 
New York Times, October 11, 2019.  
8 Press Briefing by Defense Secretary Esper and Chairman of the Joint Chiefs of Staff General Milley, October 11, 2019. 
9 “As U.S. Pulls Out of Syria, Russian Forces Swoop In,” 
Wall Street Journal, October 15, 2019. 
  
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White House Announces Full Withdrawal from Northern Syria 
On October 11, U.S. forces in the vicinity of Kobane came under Turkish artillery fire, according to U.S. 
military officials.
10 Turkey denied targeting U.S. forces deliberately, and claimed that Turkish forces were 
responding to mortar fire from “terrorist positions” near the U.S. observation post. No U.S. injuries were 
reported. On October 13, President Trump directed the full withdrawal of the approximately 1,000 
remaining U.S. troops in northeast Syria.
11  
Figure 1. Syria-Turkey Border 
 
Source: CRS using area of influence data from IHS Conflict Monitor, last revised October 15, 2019. All areas of influence 
approximate and subject to change. Other sources include U.N. OCHA, Esri, and social media reports. 
Notes: This map does not depict all U.S. bases in Syria.  
Islamic State Detainees  
Prior to the Turkish incursion, SDF forces in Syria held approximately 10,000 IS militants in custody at 
several makeshift prisons in northern Syria, and provided security at the Al Hol IDP camp and other 
locations where additional IS family members and/or supporters are among the populations (
Figure 1).
12 As Turkey prepared to launch operations in Syria, SDF leaders warned that forces previously tasked with 
securing IS detainees had been diverted to the border. Following a Turkish attack on the city of Ain Issa, 
several hundred women and children linked to the Islamic State escaped a camp for displaced persons. 
Additionally, U.S. forces reportedly were unable to execute a plan to remove about five dozen high value 
IS prisoners from Syria before withdrawing.
13   
                                                 10 “Turkey Attacks US Special Forces in Syria, Apparently by Mistake,” 
Newsweek, October 11, 2019. 
11 “U.S. Military to Withdraw From Northern Syria,” Wall Street Journal, October 13, 2019.  
12 Lead Inspector General for Operation Inherent Resolve, Quarterly Report to the U.S. Congress, April 1, 2019-June 30, 2019. 
13 “U.S. Moves to Take ‘High Value’ ISIS Detainees, Including Britons Who Abused Hostages,” 
New York Times, October 9, 
2019; “Abandoned by U.S. in Syria, Kurds Find New Ally in American Foe,” 
New York Times, October 14, 2019. 
  
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Former U.S. Kurdish Allies Join Forces with Asad Government 
The SDF, a key U.S. ally in the counter IS-campaign, said it had reached an interim agreement with the 
Asad government to defend against the Turkish advance. In a statement, the SDF announced that, “An 
agreement has been reached with the Syrian government — whose duty it is to protect the country’s 
borders and preserve Syrian sovereignty — for the Syrian Army to enter and deploy along the Syrian-
Turkish border to help the SDF stop this aggression.” Local officials in Manbij and Kobane, areas where 
U.S. forces previously had been based, confirmed that they had been asked to allow Syrian troops to 
deploy.
14 On October 14, Syrian military forces entered the towns of Tabqa and Ain Issa.
15  It is unclear 
whether the Syrian government will directly challenge Turkish military forces, or will aim primarily to 
deter Turkish expansion. It is also unclear how the agreement will impact the former U.S. ally. SDF 
leaders have said the agreement allows them to retain their military structure and control of local 
governing councils. However, the Syrian government has said the SDF must disband and merge with pro-
regime military units.
16 On October 15, Russia announced that its units were patrolling between Turkish 
and Syrian military forces near Manbij.  
U.S. Sanctions Turkish Officials 
On October 14, President Trump issued an executive order authorizing sanctions against current and 
former Turkish officials, government agencies, sectors of the Turkish economy to be determined by the 
Secretary of the Treasury, and any person found to be responsible for or engaged in the ongoing military 
operations in northeastern Syria, intimidation of displaced persons in the region, or interference in 
democratic processes, along with financial institutions or other parties deemed to be assisting any 
designated individuals.
17 According to the President, the order authorizes 
[Sanctions on] those who may be involved in serious human rights abuses, obstructing a ceasefire, 
preventing displaced persons from returning home, forcibly repatriating refugees, or threatening the 
peace, security, or stability in Syria. The Order will authorize a broad range of consequences, 
including financial sanctions, the blocking of property, and barring entry into the United States.
18 
The Treasury Department designated for sanctions Turkey’s defense and energy ministries and their 
ministers, as well as Turkey’s interior minister.
19 The President also raised steel tariffs on Turkey and 
announced an immediate stop to U.S. negotiations with Turkey on a $100 billion trade deal.
20 That same 
day, Vice President Mike Pence said that the President had called on Turkish President Erdogan to cease 
fire in Syria, and that Pence and National Security Advisor Robert O’Brien would travel to Turkey in an 
attempt to broker a stop to hostilities involving Turkey and the SDF.
21 
                                                 14 “U. S.-allied Kurds strike deal to bring Assad’s Syrian troops back into Kurdish areas,” 
Washington Post, October 13, 2019 . 
15 “Syrian troops enter key towns in northeast under deal with Kurds,” 
Washington Post, October 14, 2019.  
16 “4 big questions about Syria’s future,” 
New York Times, October 15, 2019.  
17 White House, Executive Order on Blocking Property and Suspending Entry of Certain Persons Contributing to the Situation in 
Syria, October 14, 2019. 
18 White House, Statement from President Donald J. Trump Regarding Turkey’s Actions in Northeast Syria, October 14, 2019. 
19 Department of the Treasury, Executive Order on Syria-related Sanctions; Syria-related Designations; Issuance of Syria-related 
General Licenses, October 14, 2019. 
20 White House, Statement from President Donald J. Trump op. cit. footnote
 18. 21 Keith Johnson and Elias Groll, “Trump’s Weak Sanctions May Only Help Erdogan,” foreignpolicy.com, October 14, 2019. 
  
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Conflict Status 
Idlib Province Remains Safe Haven for Al Qaeda in Syria 
Administration officials continue to describe Syria’s northwestern province of Idlib, which has been 
under opposition control since 2015, as “a major terrorist concern.”
22 While a range of opposition groups 
operate in the province, U.S. officials in 2017 described Idlib as “the largest Al Qaeda safe haven since 
9/11.”
23 U.S. initiatives in Idlib aimed at countering violent extremism (CVE) were halted in May 2018 as 
part of a broader withdrawal of U.S. assistance to northwest Syria.
24 In January 2019, the Al Qaeda-linked 
group Haya’t Tahrir al Sham (HTS) seized large areas of Idlib province from rival armed groups. In early 
2019, the U.S. intelligence community also highlighted another Al Qaeda-linked group in Syria known as 
Hurras al Din (“Guardians of Religion”, HD). While HTS and HD have occasionally clashed in Idlib, 
some analysts have assessed that the two groups “serve different functions that equally serve al-Qa`ida’s 
established objectives: one [HD] appeals to hardened jihadis with an uncompromising doctrine focused 
on jihad beyond Syria and one [HTS] appeals to those focused on the Syrian war.”
25  
In February 2019, the two groups signed an accord pledging broader cooperation.
26  In June and August 
of 2019, CENTCOM announced two U.S. strikes against “al-Qaida in Syria (AQ-S) leadership” in Aleppo 
and Idlib provinces, respectively.
27 The second strike  
targeted AQ-S leaders responsible for attacks threatening U.S. citizens, our partners, and innocent 
civilians. [...] Northwest Syria remains a safe haven where AQ-S leaders actively coordinate terrorist 
activities throughout the region and in the West.
28  
In September 2019, the U.S. government named HD as a Specially Designated Global Terrorist entity 
pursuant to Executive Order 13224, as amended by Executive Order 13886. 
Asad Government Reasserts Control; Limited Progress on Political Settlement  
The U.S. intelligence community’s 2018 Worldwide Threat Assessment stated, “The conflict has 
decisively shifted in the Syrian regime’s favor, enabling Russia and Iran to further entrench themselves 
inside the country.”
29 The Trump Administration continues to state its intent to refrain from supporting 
reconstruction efforts in Syria until a political solution to the conflict is reached in accordance with U.N. 
Security Council Resolution 2254, which calls for constitutional reform and U.N.-supervised elections.
30 In 2019 the U.S. intelligence community assessed that Asad has “little incentive” to make “anything more 
than token concessions to the opposition or to adhere to UN resolutions on constitutional changes that 
                                                 
22 Briefing by Special Envoy for the Global Coalition to Defeat ISIS Ambassador James F. Jeffrey and Counterterrorism 
Coordinator Ambassador Nathan A. Sales, August 1, 2019. 
23 Brett McGurk, Special Presidential Envoy for the Global Coalition to Counter ISIS, at the Middle East Institute, July 27, 2017. 
24 “Trump administration ends aid for northwestern Syria,” CBS, May 18, 2018. 
25 Hassan Hassan, “Two Houses Divided: How Conflict in Syria Shaped the Future of Jihadism,” 
CTC Sentinel, October 2018.  
26 Thomas Joscelyn, “Analysis: Hay’at Tahrir al-Sham and Hurras al-Din reach a new accord,” 
Long War Journal, February 15, 
2019. 
27 Statement from U.S. Central Command on strike against al-Qaida in Syria, June 30, 2019. 
28 Statement from U.S. Central Command on U.S. Forces strike against al-Qaida in Syria leadership in Idlib, Syria, Aug. 31, 
2019. 
29 Worldwide Threat Assessment of the U.S. Intelligence Community, February 13, 2018. 
30 New York Foreign Press Center Briefing by James Jeffrey, Special Representative for Syria Engagement and Special Envoy to 
the Global Coalition to Defeat ISIS, “Readout and way forward from the U.N. General Assembly,” September 27, 2019.  
  
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Asad perceives would hurt his regime.”
31 In September 2019, the U.N. Special Envoy to Syria, Geir 
Pedersen, announced the formation of a 150-member Syrian committee that will be tasked with drafting a 
new constitution, per UNSCR 2254. The committee, whose formation took almost two years, consists of 
50 opposition members, 50 representing the Asad government, and 50 representing Syrian civil society. 
 
Humanitarian Conditions Deteriorate32 
As of October 2019, 11.7 million Syrians (59 percent of Syria’s current estimated internal population) 
were in need of humanitarian assistance, 5.6 million Syrians were registered as refugees in neighboring 
countries, and 6.2 million were internally displaced.
33 Areas of particular concern include: 
Northeast Syria. U.N. agencies stated that at least 160,000 people are reported to have been displaced 
since the start of Operation Peace Spring on October 9.
34 At the same time, shelling and road closures 
have forced humanitarian organizations to suspend or scale back their operations in the area. As of mid-
October, all international aid groups had withdrawn their personnel, according to the Kurdish Red 
Crescent.
35 Iraqi authorities reported that several hundred people have crossed the border into 
northwestern Iraq.  
Idlib. The province
 is home to an estimated three million people, half of whom are children according to 
U.N. reporting.
36 U.N. officials have described Idlib as a “dumping ground” for fighters and civilians 
evacuated or displaced from formerly opposition-held areas in other parts of the country. Syrian military 
forces have escalated operations in Idlib in 2019, displacing more than 400,000 people—including 
150,000 children—since May, according to U.N. estimates.
37 A report issued by the U.N. Secretary 
General in August stated, “The escalation of hostilities in the north-west, combined with high levels of 
need and vulnerability, has had catastrophic humanitarian consequences for the estimated 3 million people 
living in the Idlib area.”
38 
Al Hol camp. Located in Al Hasakeh province, the camp hosts nearly 70,000 displaced persons, many of 
whom fled the Islamic State’s final outpost in eastern Syria. An estimated 94% of residents are women 
and children.
39 The International Rescue Committee reported in September that deaths of children at Al 
Hol had tripled since March, mostly due to treatable conditions such as severe malnutrition, diarrhea, and 
pneumonia.
40 Media reports from Al Hol in September 2019 suggested that IS sympathizers dominate 
parts of the camp, threatening the safety of other residents.
41 U.S. military estimates in June 2019 stated 
that 45,000 “ISIS supporters” were living in Al Hol.
42 As mentioned above, SDF leaders have warned that 
they may not have the resources to continue guarding detention facilities in light of ongoing Turkish 
operations in northeast Syria. 
                                                 
31 Worldwide Threat Assessment of the U.S. Intelligence Community, January 29, 2019. 
32 Prepared with assistance from Rhoda Margesson, Specialist in International Humanitarian Policy.  
33 USAID Syria Humanitarian Dashboard, September 13, 2019.  
34 UNOCHA Syria, Flash Update #5, October 14, 2019. 
35 “Syrian troops enter key towns in northeast under deal with Kurds,” 
Washington Post, October 14, 2019. 
36 U.N. Office for the Coordination of Humanitarian Affairs (UNOCHA), Syrian Arab Republic: Recent Developments in 
Northwestern Syria Situation Report No. 8 - as of 26 July 2019. 
37 UNOCHA, Syrian Arab Republic, Recent Developments in Northwestern Syria, Situation Report No. 13, October 8, 2019.  
38 U.N. Security Council, Report of the Secretary General, S/2019/674, August 21, 2019.  
39 UNHCR, North East Syria: Al Hol camp service mapping snapshot, August 1, 2019. 
40 “Guns, Filth, and ISIS: Syrian Camp is ‘Disaster in the Making,” 
New York Times, September 3, 2019.  
41 Ibid: “At a sprawling tent camp in Syria, ISIS women impose a brutal rule,” 
Washington Post, September 3, 2019. 
42 Lead Inspector General for Operation Inherent Resolve, Quarterly Report to the U.S. Congress, April 1, 2019-June 30, 2019. 
  
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Rukban camp abuts the Jordanian border in remote southeastern Syria near a U.S. military garrison at At 
Tanf. As of late July, approximately 25,000 people remained internally displaced at Rukban.
43 Occupants 
of Rukban are primarily women and children, and the United Nations in August reported that 
humanitarian conditions in the camp remain “dire,” due in part to a lack of access to food and basic health 
services.
44 Over the past two years, only two humanitarian convoys have been able to deliver aid to 
Rukban, due to Syrian government restrictions.
45 Some observers have argued that the United States 
should take on a greater humanitarian role at Rukban, given the proximity of U.S. military personnel at 
the nearby At Tanf garrison.
46 In an October 2019 statement, President Trump confirmed that some U.S. 
personnel will remain at At Tanf, despite the withdrawal of other U.S. military forces from Syria’s 
northeast. 
U.S. Syria Policy Pre-withdrawal 
Military Operations 
The withdrawal from northeastern Syria would leave a small contingent of U.S. forces at the At Tanf 
garrison in the tri-border area between Syria, Iraq, and Jordan “to continue to disrupt remnants of ISIS.”
47 First deployed in 2015, U.S. military forces have operated in Syria pursuant to the 2001 Authorization for 
the Use of Military Force (AUMF) and the 2002 Authorization for Use of Force against Iraq,
48 but 
without the authorization of the Syrian government. The At Tanf garrison is geographically remote from 
former U.S. areas of operation north of the Euphrates River. While IS forces are known to be active in the 
areas of central Syria north of At Tanf, this area is under the military influence of the Syrian government 
and its Russian and Iranian partners. U.S. operations in these areas thus may be contested and limited. 
The Administration has not said whether or not it will continue to use train and equip program funds to 
support U.S. partner forces operating from At Tanf.  
Building Partner Capacity 
To date, U.S. policy has focused on working “by, with, and through” local partners to address the threat to 
the United States posed by IS militants operating in Syria. The Syria Train and Equip (T&E) program is 
the primary programmatic mechanism for counter-IS operations in Syria, and has relied on the United 
States’ ability to partner with vetted Syrian opposition groups. In 2019, Congress has considered defense 
authorization legislation that would expand both the goals of the T&E program and its intended 
recipients. In a possible recognition of the shifting course of the conflict, language proposed in the House 
and Senate versions of the FY2020 NDAA
 (H.R. 2500, S. 1790) would allow the program to continue 
beyond the defeat of both the Islamic State and the Syrian opposition. (See “Pending Legislation,” below.) 
Prior to the withdrawal, U.S. Syrian partner forces numbered approximately 100,000 and included three 
primary components: 1) the Syrian Democratic Forces (SDF), which was the largest combat force and 
consists primarily of the Syrian Arab Coalition (SAC) and the PKK-linked Kurdish People’s Protection 
                                                 
43 UNICEF Whole of Syria Crisis Situation Report - July 2019 Humanitarian Results, July 31, 2019. 
44 U.N. Security Council, Report of the Secretary General, S/2019/674, August 21, 2019. 
45 Ibid. 
46 “The United States won’t feed 30,000 starving Syrians living under its protection,” 
Washington Post, July 24, 2019.  
47 Statement from President Donald J. Trump Regarding Turkey’s Actions in Northeast Syria, October 14, 2019. 
48 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). 
  
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Units (YPG); 2) Provincial Internal Security Forces (PRISF), composed of fighters recruited from the 
provinces in northeast Syria where they were based; and 3) the Internal Security Forces (InSF), which 
operated as a wide-area security force in IS-liberated areas and was composed of units such as the Raqqah 
Internal Security Force and the Manbij Internal Security Force.
49 The Syrian government does not 
recognize any of these forces as legitimate security actors and may be seeking to coopt or demobilize 
them as Syrian government forces move into the northeast.  
Stabilization Programming 
U.S. officials previously stated that stabilization programs in IS-liberated areas are key to preventing the 
resurgence of the Islamic State. The Trump Administration ended U.S. funding for stabilization assistance 
to Syria in 2018, but had sought the continuation of some programs using non-U.S. coalition funding. The 
future of existing interagency assistance coordination platforms—the Syria Transition Assistance 
Response Team (START) and the Southern Syria Assistance Platform (SSAP) based in Turkey and 
Jordan, respectively—along with the START Forward team that had planned to resume in-country 
operations is uncertain.
50 To date, stabilization programming for areas of northeast Syria liberated from IS 
control has comprised four primary lines of effort: (1) demining, (2) promotion of local governance and 
civil society, (3) rehabilitation of basic infrastructure, and (4) promotion of economic growth and 
development. The ability of the United States and U.S. partners to pursue these efforts in areas under SDF 
and/or Syrian government control may now be limited.  
Economic Sanctions 
The United States has maintained bilateral economic sanctions on Syria since 2004 pursuant to the Syria 
Accountability Act 
(P.L. 108-175), and has imposed additional sanctions since the beginning of the 
conflict in 2011.
51 U.S. officials have described sanctions as both a tool for changing Syrian government 
behavior, and a punitive measure designed to isolate Syria in response to ongoing human rights abuses by 
the Asad government. In November 2018 and March 2019, the Department of the Treasury’s Office of 
Foreign Assets Control (OFAC) issued advisories warning of the risk of U.S. sanctions for parties 
involved in petroleum shipments to the government of Syria. OFAC stated that the United States aimed to 
“disrupt support for the Assad regime by preventing the normalization of economic and diplomatic 
relations [...] The United States is committed to isolating the Assad regime and its supporters from the 
global financial and trade system in response to the continued atrocities committed by the regime against 
the Syrian people.”
52 
Humanitarian Aid 
The United States is the largest donor of humanitarian assistance to Syria, which is exempt from the 
restrictions imposed by sanctions and other legal restrictions on aid to the Syrian government. From 
FY2012 through October 11, 2019, the United States allocated more than $9.6 billion to meet 
humanitarian needs using existing funding from global humanitarian accounts and some reprogrammed 
funding.
53 As of October, the U.N. appeal for the 2019 Humanitarian Response Plan (HRP) for Syria was 
36% funded. The 2019 Syria Regional Refugee and Resilience Plan (3RP) sought $5.5 billion and was 
27% funded. At a pledging conference for the Syria crisis held in Brussels, Belgium, from March 12 to 
                                                 
49 Lead Inspector General for Operation Inherent Resolve, Quarterly Report to the U.S. Congress, April 1, 2019-June 30, 2019. 
50 Ibid. 
51 “U.S. Relations with Syria,” State Department Bureau of Near Eastern Affairs, July 23, 2018.  
52 Department of the Treasury, “OFAC Advisory to the Maritime Petroleum Shipping Community,” March 25, 2019.  
53 USAID, “Syria – Complex Emergency,” Fact Sheet #8, Fiscal Year (FY) 2019, August 9, 2019.  
  
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14, 2019, a record $7 billion was pledged, some of which, if and when realized, is to be applied to the 
appeals mentioned above.  
Policy Implications of Withdrawal Announcement 
Potential Islamic State Resurgence 
In an interview on October 13, Former Defense Secretary James Mattis stated that “ISIS will resurge” in 
Syria absent U.S. military pressure.
54 Similarly, retired Gen. Michael Nagata—who formerly served as 
commander of U.S. Special Operations Forces in the Middle East—on October 14 described the U.S. 
withdrawal decision as “an unintended, but strategic gift to the Islamic State.”
55 Nagata previously had 
stated that the Islamic State, even following the defeat of its physical caliphate, retains more fighters than 
Al Qaeda in Iraq did during its peak.
56 (U.S. officials in August estimated the number of IS fighters to be 
15,000, split between Syria and Iraq.
57) Al Qaeda in Iraq, which became the Islamic State of Iraq, was 
weakened, but not eliminated, by the time of the U.S. withdrawal in 2011. The group re-emerged as the 
Islamic State of Iraq and the Levant (ISIL/ISIS) in 2014, and seized large swaths of territory across Syria 
and Iraq. As of mid-October, media reports suggest that the Islamic State has moved to exploit the 
security vacuum generated by the withdrawal of Kurdish and U.S. forces. IS militants set off two car 
bombs in Kurdish-held areas of Syria, including one outside a prison. Gen. Nagata stated that ongoing 
unrest and instability in neighboring Iraq “compounds the opportunity for ISIS to be a very effective 
insurgent actor in this part of the region.”
58 
New Hurdles to Counter-IS Operations 
The latest withdrawal announcement will likely challenge the ability of the United States to pursue 
counter-IS operations in Syria. On October 11, Chairman of the Joint Chiefs of Staff Gen. Mark Milley 
stated that U.S. policy was “to continue with our counter-ISIS campaign, and we are continuing those 
operations, except in that one area of the [Turkish] incursion.”
59 It was not immediately clear whether this 
remained U.S. policy following the October 13 withdrawal announcement. Turkish forces now control 
Syria’s M4 highway, the primary east-west artery in northern Syria, and the main supply line to U.S. 
forces from Iraq. Most critically, the SDF, formerly the United States’ key local partner in counter-IS 
operations, is now formally allied with the Asad government—restricting the ability of U.S. military 
forces to partner with the group moving forward.   
Uncertain Future for Stabilization Programs 
While U.S. officials have described stabilization programs in IS-liberated areas as key to preventing the 
Islamic State’s resurgence, it is unlikely that U.S. programs in these areas will be able to continue as the 
region falls under Syrian government control. It is uncertain whether stabilization programs funded by 
                                                 
54 “Mattis: ISIS will surge back after Trump’s Syria withdrawal,” 
Politico, October 13, 2019.  
55 LTG. Nagata (Ret.) Explains the Consequences of a U.S. Withdrawal from Syria, Institute for the Study of War, October 14, 
2019.  
56 “ISIS Will Benefit from US Withdrawal, Says Retired 3-Star Who Helped Train Syrian Rebels,” 
Defense One, October 7, 
2019. 
57 Briefing by Special Envoy for the Global Coalition to Defeat ISIS Ambassador James F. Jeffrey and Counterterrorism 
Coordinator Ambassador Nathan A. Sales, August 1, 2019. 
58 “ISIS Will Benefit from US Withdrawal, Says Retired 3-Star Who Helped Train Syrian Rebels,” 
Defense One, October 7, 
2019.  
59 Press Briefing by Defense Secretary Esper and Chairman of the Joint Chiefs of Staff General Milley, October 11, 2019. 
  
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U.S. coalition partners will continue in these areas. The absence of stabilization programming in northeast 
Syria—where critical infrastructure was badly damaged as part of the U.S.-led campaign against the 
Islamic State—could leave local residents vulnerable and/or susceptible to recruitment by extremist 
groups. On October 12, the Administration announced that it was releasing $50 million “to protect 
persecuted ethnic and religious minorities, and advance human rights” in Syria and expressed its “hope 
that regional and international partners will continue their contributions as well.”
60 
Figure 2. Syria 
 
Source: CRS using area of influence data from IHS Conflict Monitor, last revised October 15, 2019. All areas of influence 
approximate and subject to change. Other sources include U.N. OCHA, Esri, and social media reports. 
Notes: This map does not depict all U.S. bases in Syria. 
                                                 
60 Statement from the White House Press Secretary, October 12, 2019. 
  
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