Yemen: Conflict, Red Sea Attacks, and U.S. Policy

Yemen is a conflict-afflicted nation along the strategic Bab al Mandab Strait, one of the world's most active shipping lanes. Since 2015, a civil war has pitted the Iran-backed Houthi movement against Yemen's internationally recognized government, its backers, and other anti-Houthi forces. Foreign intervention complicates the conflict, which has contributed to what United Nations agencies have described as "one of the largest humanitarian crises in the world." An uneasy truce has frozen conflict lines since 2022 (Figure 1). The Iran-backed Houthis have launched numerous attacks on international shipping since October 2023, ostensibly to compel Israel to end its war with Hamas. U.S.-led coalition patrol operations and counterstrikes seek to restore security in the Red Sea corridor, but Yemen's underlying conflict remains unresolved and the Houthis could pose long-term threats. In March 2025, President Donald Trump ordered an expanded campaign of military strikes against Houthi targets. The Houthis vowed to retaliatefrom October 2023 to December 2024, before pausing these attacks for months then resuming them in July 2025. The Houthis continue to launch strikes against targets in Israel ostensibly to compel Israel to end its war with Hamas. From March to May 2025, U.S. forces expanded strikes against the Houthis to compel an end to Houthi maritime attacks. The Houthis agreed to end attacks on U.S. vessels in exchange for a halt to U.S. strikes under an Oman-mediated truce. Yemen's underlying conflict remains unresolved, and the Houthis pose enduring threats to shipping and to U.S. partners.

Overview and Key Stakeholders

Long-running Yemeni disputes over governance and energy resources have deepened since 2015 amid foreign influence and intervention. The Republic of Yemen was formed by a 1990 merger of the Sana'a-led Yemen Arab Republic (a former Ottoman province, then Zaydi Shia-ruled kingdom) and the Aden-led People's Democratic Republic of Yemen (a former British colony and protectorate, then independent Marxist regime). North-south tensions and conflict have recurred since the 1960s, and a southern independence movement remains active. Tribal networks and local actors are the most influential parties in many areas of the country.

Arab Spring-era protests and unrest led the president of the Republic of Yemen Government (ROYG) to resign in 2012. A UN-mediated transition and national dialogue sought to broker new governing arrangements. The Houthi movement (alt. Ansar Allah or Partisans of God), a north Yemen-based Zaydi Shia network, opposed UN-backed outcomes and resumed an insurgency. In 2014, the Houthis seized the capital, Sana'a, and later advanced on Aden. ROYG leaders fled and requested international intervention. In March 2015, a coalition led by Saudi Arabia began a military campaign against the Houthis, whose attacks across Yemen's borders grew in complexity and scope with deepening support over time from Iran. The United States has provided logistical, intelligence, and advisory support to the coalition, but ended aerial refueling and some arms sales to Saudi Arabia in response to civilian casualties and congressional action.

In 2019, tensions between anti-Houthi forces in the ROYG (backed by Saudi Arabia) and the separatist Southern Transitional Council (STC, backed by the United Arab Emirates) led to open warfare. A 2020 power-sharing agreement formed a coalition government. Since 2022, an eight-person Presidential Leadership Council (PLC) has led Yemen's internationally recognized government. That year, the ROYG and Houthis signed a truce, halting most fighting and establishing humanitarian measures. Lines of conflictcontrol, in some areas mirroring Yemen's pre-unification borders, have been static (Figure 1). The Sunni Islamist Islah Party and National Resistance leader Tariq Saleh oppose the Houthis and hold PLC seats. Al Qaeda in the Arabian Peninsula (AQAP) and the Islamic State remain active.

Figure 1. Yemen: Key Actors and Approximate Areas of Influence As of March 2025

Sources: CRS using ESRI and U.S. Department of State map data. Areas of Influence based on ACAPS data and UN and media reports. Notes: STC = Southern Transitional Council. AQAP = Al Qaeda in the Arabian Peninsula. All areas approximate and subject to change. Shading includes lightly populated and uninhabited areas.

Conflict Status and U.S. Diplomacy

Since 2015, conflict has caused widespread humanitarian suffering and significant infrastructure damage in Yemen, long the Arab world's poorest country. In 2021, the UN estimated that 377,000 people had died as a result of the conflict (including combatants) and that nearly 60% of deaths were from non-military causes, such as lack of food, water, or health care. Foreign observers have denounced human rights violations attributed to all parties. Since the truce expired in 2022, fighting has not returned to "pre-truce levels." Houthi cross-border attacks into Saudi Arabia and Saudi-led coalition airstrikes ceased, though the Houthis threaten to strike countries that could support U.S. operations. In 2021, President Donald Trump designated the Houthis a Specially Designated Global Terrorist entity (SDGT) and Foreign Terrorist Organization (FTO). President Joe Biden reversed these steps before redesignating the Houthis as an SDGT in 2024. President Trump redesignated the Houthis as an FTO in March 2025.

Houthi Attacks and U.S. Responses

Following the October 7, 2023, Hamas-led attacks on Israel, and Israel's military operations in Gaza, the Houthis began targeting Israeli territory as well as commercial ships transiting the Bab al Mandab Strait. The Houthis claimed to have targeted Israel-linked vessels, but they have targeted vessels from many countries, diverting more than half of the pre-conflict maritime traffic from the Red Sea and driving up shipping global firms' costs, insurance premiums, and ocean freight rates. UN Security Council Resolution 2722 (2024) demands the Houthis cease attacks. The U.S. State Department has said "the Houthis must permanently cease all attacks in the Red Sea and surrounding waterways without exception." The Houthis halted attacks following the January 2025 Israel-Hamas ceasefire, but resumed attacks on Israel in March, in protest of Israeli military operations in Gaza.

U.S. forces have intercepted Houthi-launched projectiles, prevented attempted Houthi seizures of vessels, struck Houthi targets in Yemen, and led the Operation Prosperity Guardian coalition patrolling the southern Red Sea. On March 15, U.S. forces began a military campaign the Administration intendsmaritime traffic from the Red Sea and driving up global shipping costs and insurance premiums. The Houthis halted attacks following the January 2025 Israel-Hamas ceasefire, but resumed attacks on land-based targets in Israel in March. In July 2025, the Houthis resumed maritime attacks, sinking two vessels and capturing some crew members. UN Security Council Resolution 2722 (2024) demands the Houthis cease attacks, and, in July 2025, the Council voted to extend related reporting provisions until January 2026. Through 2024, U.S. forces intercepted Houthi-launched projectiles, prevented some attempted Houthi seizures of vessels, led coalition patrol operations, and struck Houthi targets in Yemen. U.S. forces took responsibility for Red Sea presence and information sharing missions under Operation Prosperity Guardian in February 2025. On March 15, 2025, U.S. forces began a military campaign the Administration intended to compel the Houthis to end their attacks and eliminate their capability to threaten maritime transit. The Houthis have vowed to resist, have attempted to strike U.S. ships, have continued to attack Israel, and claim to have shot down U.S. unmanned aircraft.

Foreign support and accumulated expertise may allow the Houthis to pose enduring maritime security risks. U.S. sanctions to date illuminateactions target the group's diverseglobal support networks. U.S. officials say Iran has resupplied the Houthis and provided targeting information and military advicehave described Iran's efforts to supply the Houthis with weaponry, targeting information, and military advice. In July, U.S. officials announced that Yemeni forces had seized 750 tons of munitions and hardware intended for Houthi use. In 2024, a U.S. official said, "Iran does not control the Houthis" but without Iran's assistance, "the Houthis would struggle to effectively track and strike vessels navigating shipping lanes through the Red Sea and Gulf of Aden."

Humanitarian Situation

The UN reports that 19.5 million Yemenis (more than half the population) need humanitarian assistance and almost half of Yemenis are food insecure. Yemen relies on wheat and rice imports, making food supplies vulnerable to international shocks. In Januaryprotection. In May 2025, UN agencies and humanitarian organizations warned that without changes to a trend of "drastic cuts" to funding, needs in Yemen "will worsen ... and will likely cause an increase in morbidity and mortality in the coming months." As of July 22, 2025, the annual UN humanitarian funding appeal for Yemen totaledsought $2.47 billion to provide life-saving assistance to 10.5 million people and was 13.1% funded. Limits on movement and bureaucracy constrain humanitarian access and affect aid delivery, largely in Houthi-controlled areas, where the Houthis periodically detainhave detained UN and aid workers. Terrorism designations, U.S. assistance policy changes, or escalation of conflict could affect commercial trade and humanitarian operations.

Counterterrorism

As of 2024, the State Department assessed that the "security vacuum" in Yemen had empowered Yemen-based terrorist groups,Insecurity in Yemen creates opportunities for Yemen-based Al Qaeda and Islamic State members. Iran's Islamic Revolutionary Guard Corps-Qods Force, and Lebanon's Hezbollah. UN monitors described AQAP in December 2024 as having renewed a pact with the Houthis providing for "mutual non-aggression, prisoner exchanges and the movement of weapons." and Lebanon's Hezbollah also have operated in Yemen. UN monitors and the U.S. military report that the Houthis have pursued mutually beneficial arrangements with Al Qaeda forces in Yemen and "like-minded groups on the coast of Africa."

Yemen and the 119^th Congress

The 2025 National Defense Authorization Act (P.L. 118-159) did not extend a previous ban on U.S. in-flight refueling of aircraft engaged in hostilities in Yemen's civil war that had been renewed since FY2020. Supplemental appropriations for FY2024 (P.L. 118-50) and the Full-Year Continuing Appropriations and Extensions Act, 2025continuing appropriations for FY2025 (P.L. 119-4) provide additional defense funds for U.S. Central Command that may support Yemen-related operations. President Trump, like President Biden, has asserted authority to direct military operations in Yemen pursuant to the President's constitutional authority as Commander in Chief and Chief Executive. In April, some Representatives and Senators sought details from the Administration on its strategy and plans. Through oversight and appropriations, Congress may evaluate, support, or constrain executive branch efforts to weaken Houthi capacity, interdict Iranian support, or address humanitarian conditions.