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 retaliate.
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 conflict, 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.
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 Biden reversed these steps before redesignating the Houthis as an SDGT in 2024. President Trump redesignated the Houthis as an FTO in March 2025.
On March 6, 2025, UN Special Envoy for Yemen Hans Grundberg said parties to the conflict were "pre-positioning themselves publicly for military confrontation." He noted the U.S. redesignation of the Houthis as an FTO and said, "We are at a point in time where the fear of a return to full conflict is palpable." On March 17, the UN Secretary General expressed concern about new U.S. strikes in Yemen and said the UN "calls for utmost restraint and a cessation of all military activities. Any additional escalation could exacerbate regional tensions, fuel cycles of retaliation that may further destabilize Yemen and the region and pose grave risks to the already dire humanitarian situation."
Through 2024, U.S. diplomats, led by Special Envoy for Yemen Ambassador Timothy Lenderking, said they sought to transform the truce into a durable ceasefire, enable a political solution, and support UN mediation. In March 2025, U.S. Secretary of Defense Pete Hegseth stated that U.S. efforts seek to assure freedom of navigation and said, "we don't care what happens in the Yemeni civil war." An April press report cited unnamed U.S. officials as saying the Administration had not decided whether to support ground operations by Yemeni forces against the Houthis.
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 intends 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 illuminate the group's diverse support networks. U.S. officials say Iran has resupplied the Houthis and provided targeting information and military advice. 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 January 2025, the annual UN humanitarian funding appeal for Yemen totaled $2.47 billion to provide life-saving assistance to 10.5 million people. Limits on movement and bureaucracy constrain humanitarian access and affect aid delivery, largely in Houthi-controlled areas, where the Houthis periodically detain 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, 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."
Yemen and the 119th Congress
The 2025 National Defense Authorization Act (P.L. 118-159) did not extend a 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, 2025 (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.