A Timeline of the Yemen Crisis, from the 1990s to the Present

Early Years: Saleh and the Houthis

1990’s – After the reunification of Yemen, Ali Abdullah Saleh transitions from president of North Yemen—a post he had held since 1978—to president of the Republic of Yemen. At the same time, the Zaidi-Shia group Ansar Allah—or the Houthis—gradually gain power; the group’s rise has the tacit support of President Saleh.

1994: Civil War – Just years after the reunification of Yemen, the unintegrated armies of the north and the south face off, resulting in a brief civil war that resulted in the defeat of the southern army and shored up Yemen’s reunification.

2000 – Saleh reaches a border demarcation agreement with Saudi Arabia (Treaty of Jeddah) and seeks to disarm the Houthis, whom he had viewed previously as a useful cudgel against Saudi interference in Yemen.

2004-2010: Houthi Rebellion

Tensions run high between Saleh’s government and the Houthis—led by Hussein Badreddin al-Houthi—after Saleh’s border deal with Saudi Arabia. Al-Houthi eventually leads a rebellion against the Yemeni government in 2004.

June-September 2004 – Starting in June 2004, Saleh’s government begins arresting hundreds of Houthi members and issues a reward for Hussein Badreddin al-Houthi’s arrest. Fighting continues until al-Houthi is killed in September.

March-June 2005 – Fighting between the Houthis—now led by Hussein’s brother, Abdul-Malik al-Houthi—and government forces surges, leaving hundreds dead. Fighting ceases after the sides reach an agreement, resulting in the surrender of the Houthis’ top military commander.

2005-2006 – Sporadic clashes between the government and the Houthis continue, but in March 2006, Saleh grants amnesty to 600 Houthi fighters. Saleh goes on to win the 2006 election.

January-June 2007 – Early in 2007, the Houthi rebels and Saleh’s government again find themselves at odds. Fighting continues for five months until Abdul-Malik al-Houthi reaches a ceasefire agreement with Saleh with the help of Qatar.

April-July 2008 – The ceasefire had not turned a year-old when more fighting breaks out between the government and the rebels. By July, Ali Abdullah Saleh declares an end to the fighting in the Houthi-dominated Saada governorate.

2009-2010: Operation Scorched Earth – In August 2009, the Yemeni military launches Operation Scorched Earth to crush the Houthi rebellion in Saada. At this point, Houthi rebels begin fighting with Saudi forces in cross-border clashes. Fighting continues until, after rounds of offers and counteroffers, Saleh’s government agrees to a ceasefire with Abdul-Malik al-Houthi and the rebels in February 2010. The Yemeni military simultaneously carries out Operation Blow to the Head, a crackdown on both the rebels and al-Qaeda in the Arabian Peninsula (AQAP).

September 2010 – Government forces besiege the governorate of Shabwa in southeast Yemen to root out AQAP militants.

2011: Arab Spring Reaches Yemen

January 2011 – Demonstrations calling for the end of Saleh’s 33-year rule begin. Saleh offers some concessions—promising not to seek reelection—but the protests spread. Security forces and Saleh supporters launch a crackdown that eventually leaves between 200 and 2,000 people dead.

April 2011 – Saleh’s General People’s Congress (GPC) agrees to a Gulf Cooperation Council (GCC)-brokered deal to hand over power, but the president refuses to sign on. This prompts the influential Hashid tribal federation and several army commanders to back the opposition, after which clashes erupt in Sanaa.

June 2011 – Saleh is seriously injured in a bombing and travels to Saudi Arabia for medical treatment.

September 2011 – Saleh returns to the presidential palace amid renewed clashes. It is not until November 2011 that he signs a deal that has his deputy, Abdrabbuh Mansour Hadi, assume power and form a unity government.

February 2012 – Hadi is sworn in for a two-year term as president after an election in which he stood unopposed.

Post-Arab Spring: Unity Government and Houthi Takeover

January 2014 – The National Dialogue Conference concludes after ten months of deliberations, agreeing to a document on which the new constitution would be based.

February 2014 – A presidential panel approves a political transition plan for Yemen that organizes the country into a federation of six regions.

August 2014 – Following two weeks of anti-government protests, President Hadi dissolves his cabinet and overturns a controversial rise in fuel prices.

September-October 2014 – The Houthis take control over most of Yemen’s capital, Sanaa. The following month the rebels seize the Red Sea port city of Hodeida.

January 2015 – After being placed under house arrest by the Houthis, Hadi resigns as president. Despite previous attempts to craft a power-sharing agreement between Hadi and the Houthis, the two had continued to clash. The Houthis later reject a draft constitution proposed by Hadi’s government.

February 2015 – The Houthis take control of the Yemeni government, a move swiftly denounced by the United Nations. President Hadi flees the presidential palace in Sanaa and escapes to Aden, where he later rescinds his resignation, declaring himself the legitimate president, and deems the Houthi takeover a “coup.”

March 2015 – The Islamic State claims its first major attacks in Yemen, setting off two suicide bombs at Shia mosques in Sanaa. The Houthis start an offensive against government forces, advancing toward southern Yemen. President Hadi flees Aden and takes refuge in Saudi Arabia. Shortly thereafter, the Houthis seize parts of Taiz.

Saudi-led Coalition and Civil War

March 2015: Operation Decisive Storm – After repeated pleas from Hadi, a Saudi-led coalition of Arab states—including the United Arab Emirates, Egypt, Morocco, Jordan, Bahrain, Sudan, and Kuwait—initiates Operation Decisive Storm in support of the ousted president. The coalition launches air strikes against Houthi targets, deploys small ground forces, and imposes a naval blockade. The United States announces its intention to aid the coalition’s efforts.

April 2015: Operation Restoring Hope – The coalition declares an end to Operation Decisive Storm. Saudi Arabia announces it would move on to a phase described as Operation Restoring Hope. Despite the announcement, the Saudi-led coalition continues to bomb Houthi positions and the United States increases its arms sales for the Saudi campaign in Yemen.

April 2015 – Despite the bombing campaign, the Houthis capture the city of Ataq. After three Saudi officers die in a Houthi attack at the Saudi border, Saudi Arabia boosts its border security. The Houthi fighters also condemn a UN Security Council resolution imposing an arms embargo on the group, calling the decision an act of “aggression.”

May 2015 – Ali Abdullah Saleh had previously been accused of siding with the Houthi rebels in support of Hadi’s ouster; in May, Saleh and Yemeni forces loyal to him announce a formal alliance with the Houthis. The Saudis and Houthis agree to a five-day “humanitarian ceasefire.” US President Barack Obama convenes a GCC meeting at Camp David to resolve the crisis in Yemen, but only two states send their leaders.

August 2015 – After months of fighting with Sunni tribesmen and AQAP militants, the Houthis take control of the entire Shabwah governorate.

September 2015 – President Hadi returns to Aden after Saudi-backed government forces and those loyal to Hadi recapture the port city from Houthi forces.

April 2016 – The United Nations sponsors talks between the Hadi government and the coalition of Houthis and former President Saleh’s General People’s Congress.

October 2016-May 2017 – Both sides of the conflict allegedly break ceasefires. The United Nations and others try to broker peace talks and political resolutions. The Houthis claim responsibility for firing missiles into Saudi Arabia, including at the capital, Riyadh.

May-November 2017 – Humanitarian agencies and watchdogs decry the Yemen crisis as one of the worst humanitarian emergencies in the world. There are thousands of civilians dead and wounded, an outbreak of cholera, and a potential famine that would leave thousands on the brink of starvation.

November 2017 – Saudi Arabia intercepts a missile fired toward its airport in Riyadh and blames the Houthis, Iran, and Lebanon’s Hezbollah for escalating the war.

December 2017 – After Saleh had reversed course and sided with the Saudi-led coalition, fierce fighting in Sanaa between the Houthis and forces loyal to Saleh leaves the former president dead. The Houthis control much of northern Yemen but face stiff opposition from the Saudi-led coalition. President Hadi—whose loyalists control much of south Yemen—has called for a popular uprising against Houthi rule in the north. Saleh’s son, Ahmed Ali Saleh, has vowed revenge against the Houthis for his father’s assassination.

January 2018 – In a firefight, the Southern Transitional Council (STC), the United Arab Emirates-backed separatist movement seeking a revival of the formerly independent South Yemen, seizes control of Aden, Yemen’s main southern city and government headquarters. By March, 22 million Yemenis require humanitarian aid.

February 2018 – The United Nations appoints longtime British diplomat Martin Griffiths as Special Envoy of the Secretary-General for Yemen.

March-May 2018 – Fighting escalates along Yemen’s western coast and dozens are killed in Saudi air strikes and security raids. A Saudi-led coalition drone strike kills Saleh Ali al-Sammad, president of Yemen’s Supreme Political Council, making him the most senior Houthi casualty since the coalition began its activities in 2015. International opposition to the coalition’s operations grows after an air raid kills more than 20 at a wedding party. In May, UAE forces take over the island of Socotra, occupying the airport and seaport and causing tensions with Yemeni government officials.

June-July 2018 – Yemeni President Abdrabbuh Mansour Hadi meets with UAE Crown Prince Mohammed bin Zayed Al Nayhan and, by July, the coalition launches an offensive on the port city of Hodeida.

August-October 2018 – International furor over the Saudi-led coalition’s war in Yemen grows after an air raid strikes a school bus, killing 40, mostly children. Public opinion of US support for the war effort in the United States plummets as it is reported that the bomb used in the air raid was US-supplied. In October, US resident and Washington Post columnist Jamal Khashoggi is assassinated by Saudi agents in Istanbul, raising additional questions about US support for Riyadh’s war on Yemen. UN efforts to mediate between the Yemeni government and the Houthi rebels in Geneva, Switzerland are fruitless.

November-December 2018 – The US political establishment begins to agitate for withdrawing US support from the Saudi-led coalition in Yemen. Former Obama Administration officials—including future Secretary of State Antony Blinken, future UN Ambassador nominee Linda Thomas-Greenfield, and future National Security Advisor to President Joe Biden Jake Sullivan—sign an open letter expressing remorse for their support for the war and urging all sides to end the fighting. In December 2018, the US Senate, for the first time, votes to invoke the War Powers Resolution to force the US military to end its participation in the Yemen war.

Later that month, after UN-mediated talks, the Yemeni government and the Houthis sign the Stockholm Agreement that includes prisoner swaps, a mutual redeployment of forces away from Hodeida Port, and a committee to discuss the contested city of Taiz. The cease-fire is set to take effect on December 18. Overall, the Stockholm Agreement fails to achieve its goals and neither side agrees to withdraw from Hodeida.

January-June 2019 – Fighting continues. Houthis launch a drone attack on Al-Anad Air Base north of Aden, injuring dozens and killing the head of Yemeni intelligence. By June, the UAE unilaterally scales back its military presence in Yemen while continuing to support the STC, which had seized more power in Aden. Meanwhile, the Houthis step up efforts to attack Saudi territory, including launching missiles at oil installations and airports. Saudi and Yemeni forces capture Abu Osama al-Muhajer, leader of the so-called Islamic State-Yemen Province (IS-YP).

In Washington, Secretary of Defense James Mattis’s resignation in December 2018 takes effect in February 2019, marking an end to the Trump Administration’s efforts to engage in the Yemen peace process. In April, President Donald Trump vetoes a bipartisan congressional measure that would force the US military to end its role in the Yemen war.

July-September 2019 – The UAE announces it has completed its troop drawdown in Yemen, but by August, the STC effectively assumes control of the southern governorates of Aden, Abyan, and Shabwa. By the end of August, UAE forces conduct air raids against Yemen government forces headed to Aden to regain control.

In August, the Houthis launch “Operation Victory from God” against Saudi-led forces and the group continues to escalate its attacks on Saudi oil installations. In September, the Houthis claim to have used drones to bomb oil processing facilities in Abqaiq and Khurais in eastern Saudi Arabia. The attacks result in Saudi Arabia losing about half of its output capacity and, while the Houthis take credit for the aggression, the international community blames Iran because it was thought to have provided the technical expertise needed to carry out such attacks.

November 2019 – In an effort to end the fighting between ostensible coalition partners in southern Yemen, Saudi Arabia and the UAE broker a power-sharing agreement between their respective partners in the Yemen government forces and the STC. The Riyadh Agreement is signed in early November, but by December, clashes between the two resume.

January-February 2020 – Fighting between the Saudi-led coalition and the Houthis picks up. Houthi forces carry out missile attacks on military training camps and in Saudi Arabia’s southern provinces. They claim to “liberate” roughly 1,550 square miles of territory in the al-Jawf and Marib governorates from Saudi-led forces, a claim the coalition denies.

March 2020 – Houthi forces capture the strategic city of al-Hazm in the al-Jawf offensive and Saudi forces carry out a retaliatory air strike on Sanaa. This occurs as the United Nations urges maintaining the cease-fire during the COVID-19 pandemic to prevent its spread in Yemen.

The Trump Administration announces a freeze on $73 million in humanitarian aid to Yemen, fearing the Houthi rebels would control the assistance.

April-May 2020 – In April, Saudi Arabia initiates a unilateral two-week cease-fire to mitigate the risks of the new coronavirus pandemic. Days later, Yemen records its first known case of COVID-19. Despite the cease-fire, the Houthis and the Saudi-led coalition are accused of carrying out attacks. In the south, the STC once again demands self-rule, breaking its agreement with the national government.

June-November 2020 – In June, the Southern Transitional Council deposes the recognized government in Socotra, with government supporters decrying the move as a coup d’état. The following month, the STC says it has renounced its claim to self-rule and will return to the previously agreed-upon power-sharing structure.

In October, the warring sides in Yemen carry out the conflict’s largest prisoner swap. By November, Saudi Arabia and the Houthis have reportedly initiated back channel talks, with Saudi officials indicating their willingness to sign a cease-fire deal and end the Saudi air and sea blockade in exchange for the creation of a buffer zone between Houthi-controlled territory in Yemen and the kingdom’s borders. The Houthis later claim to have fired a missile at the coastal Saudi city of Jeddah.

December 2020 – The STC and the Hadi government formalize a new power-sharing agreement in Aden. Prime Minister Maeen Abdulmalik Saeed is reappointed as head of the Hadi government’s new cabinet, with seats going also to both the STC and Yemen’s Islah Party. Just weeks later, as the new cabinet arrives in Aden from Saudi Arabia, an attack on the airport kills at least two dozen people, but no ministers. The Hadi government, the STC, and much of the international community blame the Houthis for the attack and Saudi warplanes conduct retaliatory raids on Sanaa.

January 2021 – The Trump Administration uses the December attack to justify designating the Houthis as a foreign terrorist organization (FTO). The Houthis are still able to consolidate control over 70-80 percent of the Yemeni population and threaten Marib, a stronghold near the northeast corner of their control zone.

President Biden Takes a New Path

February 2021 – President Joe Biden announces changes to US policy toward Yemen, including revoking the Houthi FTO designation, declaring an end to US support for the Saudi-led coalition’s offensive operations in the conflict, appointing Timothy Lenderking as a special envoy for Yemen, supporting the UN-led peace process, and providing assurances to Saudi Arabia regarding the defense of its territory.

This timeline was created with the assistance of ACW’s Congressional Affairs Intern Gabriella Haedelt, and ACW’s Research and Analysis Intern Numan Aksoy. Photo credit: flickr/Rod Waddington