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Updated February 26, 2024
Yemen: Conflict, Maritime Attacks, and U.S. Policy
Yemen is a conflict-afflicted nation along the strategic Bab
sought to broker new governing arrangements. The Houthi
al Mandab Strait, one of the world’s most active shipping
movement (alt. Ansar Allah or Partisans of God), a north
lanes. Since 2015, a civil war has pitted the Iran-backed
Yemen-based Zaydi Shia network, opposed U.N.-backed
Houthi movement against Yemen’s internationally
outcomes and resumed the insurgent posture they had taken
recognized government, its backers, and other anti-Houthi
in previous rounds of fighting with the ROYG. In 2014, the
forces. Foreign intervention complicates the conflict, which
Houthis seized the capital, Sana’a, and later advanced on
has contributed to what United Nations agencies have
Aden. ROYG leaders fled and requested international
described as “one of the largest humanitarian crises in the
intervention. In March 2015, a coalition led by Saudi
world.” An uneasy truce has frozen conflict lines since
Arabia began a military campaign against the Houthis,
2022 (Figure 1). Houthi attacks on international shipping
whose attacks across Yemen’s borders grew in complexity
have drawn major international attention back to Yemen
and scope with deepening support over time from Iran. The
since October 2023, and have prompted U.S.-led coalition
United States has provided logistical, intelligence, and
counterstrikes. In December 2023, President Joe Biden
advisory support to the coalition, but ended aerial refueling
notified Congress that “a small number” of U.S. forces
and limited arms sales to Saudi Arabia in response to
pursue counterterrorism missions in Yemen.
civilian casualties and congressional action.
Overview and Key Stakeholders
In 2019, tensions among anti-Houthi forces in the ROYG
Long-running Yemeni disputes over governance and energy
(backed by Saudi Arabia) and the separatist Southern
resources have deepened since 2015 amid foreign influence
Transitional Council (STC, backed by the United Arab
and intervention. The Republic of Yemen was formed by a
Emirates) led to open warfare. A 2020 power-sharing
1990 merger of the Sana’a-led Yemen Arab Republic (a
agreement formed a coalition government. Since 2022, an
former Ottoman province, then Zaydi Shia-ruled kingdom)
eight-person Presidential Leadership Council (PLC) has led
and the Aden-led People’s Democratic Republic of Yemen
Yemen’s internationally recognized government. That year,
(a former British colony and protectorate, then independent
the ROYG and Houthis signed a truce, halting military
Marxist regime). North-south tensions and conflict have
operations and establishing humanitarian measures. Lines
recurred since the 1960s, and a southern independence
of conflict, in some areas mirroring Yemen’s pre-
movement remains active. Tribal networks and local actors
unification borders, remain static (Figure 1). Meanwhile,
are the most influential parties in many areas of the country.
Al Qaeda in the Arabian Peninsula (AQAP) and the
Islamic State have remained active in remote areas.
Arab Spring-era protests and unrest led the president of the
Republic of Yemen Government (ROYG) in 2012 to
resign. A U.N.-mediated transition and national dialogue
Figure 1. Yemen: Key Actors and Approximate Areas of Influence
As of January 2024
Source: CRS using ESRI and U.S. Department of State map data. Areas of Influence based on ACAPS data and U.N. and media reports.
Notes: STC – Southern Transitional Council. AQAP – Al Qaeda in the Arabian Peninsula. Al areas approximate and subject to change. Shading
includes lightly populated and uninhabited areas.
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Yemen: Conflict, Maritime Attacks, and U.S. Policy
Conflict Status and U.S. Diplomacy
Since December 31, exchanges of fire between Houthi
forces and U.S. forces and U.S. allies have resulted in
Since 2015, conflict has caused widespread humanitarian
deaths of Houthi fighters, damage to merchant vessels, and
suffering and significant infrastructure damage in Yemen,
long the Arab world’s poorest country
threats to U.S. and allied service personnel. Two U.S.
. In late 2021, the
personnel died in a January operation that intercepted a
United Nations estimated that 377,000 people had died as a
shipment of Iranian missile components to the Houthis. On
result of the conflict (including combatants) and that nearly
January 11, 2024, following the passage of U.N. Security
60% of deaths were from non-military causes, such as lack
Council Resolution 2722, U.S. and allied forces conducted
of food, water, or health care. Foreign observers have
dozens of joint strikes on Houthi targets across Yemen.
denounced human rights violations attributed to all parties
U.S. and allied strikes on Houthi military targets have
to the conflict.
continued, as have Houthi attacks on U.S. and allied vessels
Since the Houthi-ROYG truce expired in October 2022,
and commercial ships. U.S. military officials state that Iran
fighting has not returned to “pre-truce levels,” but some
is resupplying the Houthis and providing targeting
exchanges of fire and clashes have occurred. Houthi cross-
information and military advice.
border attacks into Saudi Arabia and coalition airstrikes,
Humanitarian Situation
once prominent elements of the war, largely ceased. U.S.
According to the United Nations, 18.2 million people in
diplomats, led by Special Envoy for Yemen Ambassador
Yemen (more than half of Yemenis) need humanitarian
Timothy Lenderking, say they seek to transform the truce
assistance, 4.5 million are internally displaced, and 17.6
into a durable ceasefire, enable a political solution, and
million people are food insecure. Over 90% of food is
support U.N. Special Representative for Yemen Hans
imported, making the food supply particularly susceptible
Grundberg. Grundberg told the U.N. Security Council in
to international shocks. U.N. appeals remain underfunded.
February 2024 that the maritime security crisis was slowing
The U.N. Humanitarian Response Plan appeal for Yemen
mediation efforts and warned of “a sense of foreboding
sought $4.3 billion for 2023; by January 31, 2024, it was
along several front lines, with reports of clashes,
39.5% funded. The 2024 appeal seeks $2.7 billion. Limits
mobilizations and casualties” in some areas.
on movement and bureaucracy constrain humanitarian
Risks of renewed conflict in Yemen and widening U.S.-
access, largely in Houthi-controlled areas.
Houthi clashes are evident. In addition to the diplomatic
Counterterrorism
objectives described above, U.S. policy goals in Yemen
The State Department assesses that the “security vacuum”
include restoring security to shipping lanes, interdicting
in Yemen empowers Yemen-based terrorist groups, Iran’s
Iranian aid to the Houthis, combatting transnational terrorist
Islamic Revolutionary Guard Corps-Qods Force, and
groups, and ensuring humanitarian aid delivery.
Lebanon’s Hezbollah. U.N. sanctions monitors described
Maritime Attacks and U.S. Responses
AQAP in January 2024 as “in decline” and facing
Following the October 7, 2023, Hamas attacks on Israel and
leadership losses, though senior U.S. counterterrorism
Israel’s military response in Gaza, the Houthis began
officials have noted AQAP’s post-October 7 calls for
targeting Israeli territory as well as commercial vessels
attacks on U.S. citizens and interests. In January 2024, the
transiting the Bab al Mandab Strait (see Figure 2). Initially,
Biden Administration announced that the Houthis would be
the U.S. Navy intercepted Houthi-launched projectiles and
redesignated as Specially Designated Global Terrorists
prevented attempted Houthi seizures of vessels. On
(SDGT), effective February 16. In the House, H.R. 6046
December 18, the U.S. launched Operation Prosperity
would direct the Administration to redesignate the Houthis
Guardian, a coalition formed to patrol the Red Sea. Despite
as a Foreign Terrorist Organization (FTO).
international action, continuing attacks have diverted traffic
from the Red Sea and driven up shipping firms’ costs,
Yemen and the 118th Congress
insurance premiums, and ocean freight rates.
In the 118th Congress, the 2024 National Defense
Authorization Act (P.L. 118-31) extends for one year an
Figure 2. Maritime Attacks and U.S. Responses
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. 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 measures in the House and
Senate may provide additional defense funds in part for
counter-Houthi operations. The Administration seeks to
avoid an escalation of conflict that might jeopardize peace
efforts and amplify humanitarian needs.
Christopher M. Blanchard, Specialist in Middle Eastern
Affairs
Abigail G. Martin, Research Assistant
Source: CRS, using data from U.S. Department of Defense and
media reports. Attack and response data subject to change.
IF12581
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Yemen: Conflict, Maritime Attacks, and U.S. Policy
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