Yemen in Crisis

Yemen’s internal divisions and a Saudi-led military intervention have spawned an escalating political, military, and humanitarian crisis.
Members of the Houthi movement participate in a military parade in Yemen’s capital, Sanaa.
Members of the Houthi movement participate in a military parade in Yemen’s capital, Sanaa. Mohammed Huwais/AFP/Getty Images
  • Yemen’s internationally recognized government and Iran-backed Houthi rebels are fighting for control, with a Saudi-led military coalition backing the government.
  • The country’s humanitarian crisis is said to be the worst in the world, due to widespread hunger, disease, and attacks on civilian targets.
  • The UN-backed peace process stalled in 2018, and tensions between the government and southern separatists have threatened to divide anti-Houthi forces.


Yemen faces its biggest crisis in decades with the overthrow of its government by the Houthis, a Zaydi Shiite movement, and the resulting offensive led by Saudi Arabia. The fighting, and a Saudi-imposed blockade ostensibly meant to enforce an arms embargo, has had devastating humanitarian consequences, causing more than one million people to become internally displaced and leading to cholera outbreaks, medicine shortages, and threats of famine. The United Nations calls the humanitarian crisis in Yemen “the worst in the world.”

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While the Saudi-led coalition and pro-government forces have recaptured some territory, the Houthis retain control of the capital, Sanaa, and the ongoing chaos has allowed al-Qaeda’s Arabian Peninsula franchise to establish a foothold. The Saudi intervention is driven by Iranian backing of the Houthis, and the involvement of other outside powers, including the United States, raised worries that the conflict has become a proxy war. With numerous armed factions at odds over any potential settlement, UN-led efforts to broker a halt to the fighting have faltered.

What are Yemen’s divisions?

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The modern Yemeni state was formed in 1990 with the unification of the U.S.- and Saudi-backed Yemeni Arab Republic, in the north, and the USSR-backed People’s Democratic Republic of Yemen (PDRY), to the south. The military officer Ali Abdullah Saleh, who had ruled North Yemen since 1978, assumed leadership of the new country.

Yemen faced numerous challenges to its unity. The country’s north and south had long been fractured by religious differences, experiences with colonialism, and Arabic dialects. Southern separatists seceded for several months in 1994 and reemerged in 2007 as the Southern Movement, which has continued to press for greater autonomy within Yemen. Al-Qaeda in the Arabian Peninsula (AQAP) and the related Ansar al-Sharia insurgent group have captured territory in the south and east. The Houthi movement, whose base is among the Zaydi Shiites of northern Yemen, rose up against Saleh’s government six times between 2004 and 2010.

The United States lent its support to Saleh beginning in the early 2000s, when counterterrorism cooperation became Washington’s overriding regional concern. It gave Yemen $5.9 billion in military and police aid between 2000, when the USS Cole bombing in the Yemeni port of Aden made AQAP a U.S. priority, and 2020, according to the online database Security Assistance Monitor.

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Rights groups long charged [PDF] that Saleh ran a corrupt and autocratic government. As the popular protests of the 2011 Arab Spring spread to Yemen, the president’s political and military rivals jockeyed to oust him. While Yemeni security forces focused on putting down protests in urban areas, AQAP made gains in outlying regions.

Under escalating domestic and international pressure [PDF], Saleh stepped aside in 2012 after receiving assurances of immunity from prosecution. His vice president, Abd Rabbu Mansour Hadi, assumed office as interim president in a transition brokered by the Gulf Cooperation Council (GCC), a regional organization based in Saudi Arabia, and backed by the United States. As part of the GCC’s timetable for a transition, in 2013 the UN-sponsored National Dialogue Conference (NDC) convened 565 delegates to formulate a new constitution agreeable to Yemen’s many factions. But the NDC ended after delegates couldn’t resolve disputes over the distribution of power.

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What caused the current crisis?

Several factors widened these political divisions and led to full-scale military conflict.

Subsidy backlash. Under pressure from the International Monetary Fund, which had extended to Yemen a $550 million loan premised on promises of economic reforms, Hadi’s government lifted fuel subsidies in July 2014. The Houthi movement, which had attracted support beyond its base with its criticisms of the UN transition, organized mass protests demanding lower fuel prices and a new government. Hadi’s supporters and the Muslim Brotherhood–affiliated party, al-Islah, held counterrallies.

Houthi takeover. The Houthis captured much of Sanaa by mid-September 2014. Reneging on a UN peace deal brokered that month, they consolidated control of the capital and continued their southward advance. Hadi’s government resigned under pressure in January 2015 and Hadi later fled to Saudi Arabia.

Military division. Military units loyal to Saleh aligned themselves with the Houthis, contributing to their battlefield success. Other militias mobilized against the Houthi-Saleh forces, aligning with those in the military who had remained loyal to the Hadi government. Southern separatists ramped up their calls for secession.

Saudi intervention. In 2015, with Hadi in exile, Riyadh launched a military campaign—primarily fought from the air—to roll back the Houthis and restore the Hadi administration to Sanaa.

Who are the parties involved?

The Houthi movement, named for a religious leader from the Houthi clan and officially known as Ansar Allah, emerged in the late 1980s as a vehicle for religious and cultural revivalism among Zaydi Shiites in northern Yemen. The Zaydis are a minority in the Sunni Muslim–majority country but predominant in the northern highlands along the Saudi border.

The Houthis became politically active after 2003, opposing Saleh for backing the U.S.-led invasion of Iraq but later allying with him after his resignation as president. This alliance was a tactical one: Saleh’s loyalists opposed Hadi’s UN-backed government and, feeling marginalized in the transition process, sought to regain a leading role in Yemen. Saleh won the allegiance of some members of Yemen’s security forces, tribal networks, and political establishment. But in 2017, after Saleh shifted his support to the Saudi-led coalition, he was killed by Houthi forces.

Iran is the Houthis’ primary international backer and has reportedly provided them with military support, including weapons. Hadi’s government has also accused Hezbollah, Iran’s Lebanese ally, of aiding the Houthis. Saudi Arabia’s perception that the Houthis are an Iranian proxy rather than an indigenous movement has driven Riyadh’s military intervention. But many regional specialists say that Tehran’s influence is likely limited, especially since Iranians and Houthis adhere to different schools of Shiite Islam. Iran and the Houthis share geopolitical interests: Tehran seeks to challenge Saudi and U.S. dominance in the region, and the Houthis oppose Hadi’s Saudi- and U.S.-backed government.

At Hadi’s behest in 2015, Saudi Arabia cobbled together a coalition of Sunni-majority Arab states: Bahrain, Egypt, Jordan, Kuwait, Morocco, Qatar, Sudan, and the United Arab Emirates (UAE). By 2018, the coalition had expanded to include soldiers from Eritrea and Pakistan. They launched an air campaign against the Houthis with the aim of reinstating Hadi’s government. For Riyadh, accepting Houthi control of Yemen would mean a hostile neighbor on its southern border, as well as a setback in its long-standing contest with Tehran.

After Saudi Arabia, the UAE has played the most significant military role in the coalition, contributing some ten thousand ground troops—mostly in Yemen’s south—to assist coalition fighters supplied by Eritrea, Morocco, Pakistan, Qatar, Saudi Arabia, and Sudan. However, the UAE came into conflict with its allies in August 2019, when it backed the separatist Southern Transitional Government (STC), which captured Aden. In November, Hadi and the STC president signed the Riyadh Agreement, which affirms that the factions will share power equally in a postwar Yemeni government. The separatists reneged on the deal for several months in 2020, declaring self-rule in southern regions under their influence. But they abandoned that declaration in July, instead agreeing to the formation of a new Yemeni government with STC representation under an accelerated Riyadh Agreement.

Although the U.S. Congress has long been divided on the matter [PDF], the United States has backed the Saudi-led coalition, as have France, Germany, and the United Kingdom. U.S. interests include stability in Yemen and security of Saudi borders; free passage in the Bab al-Mandeb strait, the choke point between the Arabian and Red Seas, through which more than six million barrels of oil per day passed prior to the 2020 coronavirus pandemic; and a government in Sanaa that will cooperate with U.S. counterterrorism programs. But uproar over the civilian deaths in coalition air campaigns, which often use U.S.-made weapons, and Saudi Arabia’s role in the 2018 killing of Washington Post journalist Jamal Khashoggi led the United States and other Western powers to limit some weapons sales and refueling of coalition aircraft. Lawmakers have also raised concerns that U.S.-made weapons are falling into the hands of AQAP and Houthi fighters. Yet, the United States remains Saudi Arabia’s largest arms supplier, and President Donald J. Trump has thrice vetoed bills to halt emergency arms sales to Saudi Arabia.

What is the role of al-Qaeda in the Arabian Peninsula?

AQAP has benefited from the chaos. In April 2015, it captured the coastal city of Mukalla and released three hundred inmates, many believed to be AQAP members, from the city’s prison. The militant group expanded its control westward to Aden and seized parts of the city before coalition forces recovered much of the region in April 2016. AQAP has also provided Yemenis in some areas with security and public services unfulfilled by the state, which has strengthened support for the group.

The U.S. State Department warns that Yemen’s instability has weakened counterterrorism efforts [PDF], which predate the current war and rely heavily on air strikes. Trump’s administration has launched more than 100 air strikes since his 2017 inauguration, compared to the Barack Obama administration’s 185 strikes over eight years. Analysts estimate that these strikes have killed more than one hundred civilians. The United States has also killed several high-level AQAP members, including former leader Nasser al-Wuhayshi in a 2015 strike and top official Jamal al-Badawi in 2019 for his involvement in the 2000 USS Cole bombing. In January 2020, U.S. forces killed AQAP leader Qassem al-Rimi, after AQAP claimed responsibility for a December 2019 shooting at a Florida naval base that left three American aviation students dead.

AQAP, which has been in Yemen since the early 1990s, vies for influence with the self-proclaimed Islamic State, especially in the central al-Bayda Governorate. The Islamic State marked its March 2015 entrance into Yemen with suicide attacks on two Zaydi mosques in Sanaa, which killed some 140 worshippers. Though the group has since claimed other high-profile attacks, including the assassination of Aden’s governor, its following lags behind that of AQAP. The United Nations estimates that the Islamic State’s ranks in Yemen are in the hundreds and AQAP’s in the thousands.

What has the humanitarian impact been?

With a poverty rate of more than 50 percent, Yemen was the Arab world’s poorest country even prior to the conflict. A 2019 UN report said the country’s “degree of suffering is nearly unprecedented,” with more than twenty million Yemenis struggling with food insecurity and half of those on the brink of famine. Disease has run rampant; suspected cholera cases reached some seven hundred thousand [PDF] in 2019. Though just 1,600 cases of the new coronavirus disease, COVID-19, have been officially reported, experts suspect the actual caseload is far greater. Moreover, as the pandemic rages, many countries have cut back on aid to Yemen, which has a fragile health system and an infrastructure that has been devastated in the war.

In February 2020, the UN refugee agency reported [PDF] that, since 2015, the war had displaced three million people, more than one million of whom are internally displaced. The situation has worsened under the four-year land, sea, and air blockade imposed by coalition forces, obstructing vital supplies of food and medicine to the country. The U.S.-based Armed Conflict Location and Event Data Project (ACLED) has recorded more than one hundred thousand deaths due to lack of food, health services, and infrastructure since 2015.

In addition, the United Nations has found [PDF] that both the Houthis and coalition forces have violated international humanitarian law by attacking civilian targets, including the coalition’s destruction of a hospital run by the international relief organization Doctors Without Borders. Other violations perpetrated by both sides include torture, arbitrary arrests, and forced disappearances.

What are the prospects for a solution to the crisis?

UN-backed peace negotiations have made some progress, but have failed to bring an end to the conflict. December 2018 talks in Stockholm called for a cease-fire in the vital port city of Hodeidah, the exchange of more than fifteen thousand prisoners, and the creation of a joint committee to de-escalate violence. However, attempts to implement the agreement have been ineffective. Divisions within the Saudi-led coalition have dampened hopes for a broader resolution, especially after the August 2019 seizure of Aden by the UAE-backed STC. The situation deteriorated further the following month, when the Houthis claimed responsibility for a missile attack on Saudi Aramco oil facilities. UN monitors concluded that the Houthis did not carry out the attack, which the coalition blamed on Iran. Some experts see the Houthis’ willingness to claim the attack as a sign of their increasing alignment with the Iranian regime. This could motivate Saudi Arabia to further increase its commitment to the proxy conflict, they say, especially as renewed violence in early 2020 brought territorial gains for the Houthis.

Although the Riyadh Agreement appeared to founder when the STC declared self-governance in March, the separatists’ return to the deal has raised hopes that Yemen can overcome its internal divisions. Still, peace between the internationally recognized government and the Houthis remains elusive, and experts worry that lingering friction among regional actors, including Iran, Saudi Arabia, and the UAE could mean the war will continue. The underlying causes of Yemen’s conflict will continue to prove difficult to resolve. Political factions are unlikely to compromise on the distribution of power, and militias will be reluctant to give up their arms. A lasting solution will require appeasing the three major factions: the Houthis, Hadi’s government, and the STC, each of which has unique interests. Any new government, meanwhile, will need significant foreign assistance to fight terrorist groups, rebuild the country’s devastated infrastructure, and address growing humanitarian needs amid the coronavirus pandemic.

Recommended Resources

CFR’s Global Conflict Tracker follows the latest developments in Yemen’s civil war.

The New York Times’s Declan Walsh and Tyler Hicks capture the war’s human toll.

Ohio State University’s Asher Orkaby explains how Yemen’s internal divisions were centuries in the making.

A UN Security Council–appointed panel assessed the situation in Yemen [PDF] in January 2020.

Nathalie Bussemaker contributed to this report.

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