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

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Updated October 24, 2024

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, presenting vexing challenges for policymakers to consider.

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 military operations and establishing humanitarian measures. Lines of conflict, in some areas mirroring Yemen’s pre- unification borders, remain static (Figure 1). Meanwhile, Al Qaeda in the Arabian Peninsula (AQAP) and the Islamic State have remained active in remote areas.

Figure 1. Yemen: Key Actors and Approximate Areas of Influence As of July 2024

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.

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

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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 United Nations 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 October 2022, fighting has not returned to “pre-truce levels.” Houthi cross-border attacks into Saudi Arabia and Saudi-led coalition airstrikes largely ceased. U.S. diplomats, led by Special Envoy for Yemen Ambassador Timothy Lenderking, say they seek to transform the truce into a durable ceasefire, enable a political solution, and support UN Special Envoy for Yemen, Hans Grundberg. In October 2024, Grundberg criticized Houthi maritime attacks as “wholly unacceptable” and said a “cycle of retaliation is pulling Yemen deeper into the regional conflict.” He noted “relative calm” on Yemen’s frontlines and argued that peace remains achievable.

Risks of renewed conflict in Yemen and widening U.S.- Houthi clashes are evident. In addition to the diplomatic objectives described above, U.S. policy goals in Yemen include restoring security to shipping lanes, interdicting Iranian aid to the Houthis, combatting transnational terrorist groups, and ensuring humanitarian aid delivery.

Maritime Attacks and U.S. Responses

Following the October 7, 2023, Hamas-led attacks on Israel, and Israel’s military response in Gaza, the Houthis began targeting Israeli territory as well as commercial vessels transiting the Bab al Mandab Strait (see Figure 2). UN Security Council Resolution 2722 (2024) demands the Houthis cease attacks, but attacks have continued and have damaged several merchant vessels and injured and killed some merchant crew members. While the Houthis have claimed to be targeting Israel-linked vessels, they have targeted vessels from many countries, diverting maritime traffic and driving up shipping global firms’ costs, insurance premiums, and ocean freight rates.

Figure 2. Maritime Attacks and U.S. Responses, 2023- 2024

Source: CRS, using data from U.S. Department of Defense (DOD) and media reports. As of October 2024, DOD provided aggregate weekly Houthi weapon use data rather than individual incident data. Attack and response data subject to change.

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. U.S. service personnel remain at risk from ongoing Houthi attacks. The Houthis also have threatened to resume strikes on Saudi Arabia if it supports the U.S.-led coalition.

U.S. military officials state that Iran is resupplying the Houthis and providing targeting information and military advice. According to the Defense Department, “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.” Iranian support and Houthi experience may enable the group to pose enduring risks to maritime security in the region beyond any resolution of the current crisis.

Humanitarian Situation

According to the United Nations, 18.2 million people in Yemen (more than half of Yemenis) need humanitarian assistance, 4.5 million are internally displaced, and 17.6 million are food insecure. With 90% of food imported, the food supply is susceptible to international shocks. UN appeals remain underfunded. The UN Humanitarian Response Plan appeal for Yemen sought $4.3 billion for 2023; by October 24, 2024, it was 40.9% funded. The 2024 appeal seeks $2.7 billion; by October 24, 2024, it was 46.4% funded. 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.

Counterterrorism

The State Department assesses that the “security vacuum” in Yemen empowers Yemen-based terrorist groups, Iran’s Islamic Revolutionary Guard Corps-Qods Force, and Lebanon’s Hezbollah. UN sanctions monitors described AQAP in January 2024 as “in decline” and facing leadership losses, though senior U.S. counterterrorism officials have noted AQAP’s post-October 7 calls for attacks on U.S. citizens and interests. The Biden Administration redesignated the Houthis as Specially Designated Global Terrorists (SDGT) in February 2024.

Yemen and the 118th Congress

In the 118th Congress, the 2024 National Defense Authorization Act (P.L. 118-31) extends for one year an existing ban on U.S. in-flight refueling of aircraft engaged in hostilities in Yemen’s civil war. The act also requires annual reporting to Congress on Iran’s support to the Houthis. The House adopted H.R. 6046, which would direct the Administration to redesignate the Houthis as a Foreign Terrorist Organization (FTO). Some Members support U.S. strikes on Houthi targets and new efforts to disrupt Iranian support. Others have questioned the President’s authority to order broad strikes and warn against possible unintended consequences. Supplemental appropriations for FY2024 (P.L. 118-50) provided additional defense funds that may support Yemen-related operations. In the coming year, Congress may evaluate executive branch efforts to weaken Houthi capacity to threaten sea-lanes and interdict Iranian support, while preserving longer term peace prospects and avoiding deeper humanitarian crisis.

Christopher M. Blanchard, Specialist in Middle Eastern Affairs

IF12581

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

https://crsreports.congress.gov | IF12581 · VERSION 13 · UPDATED

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