Easily overlooked amidst the news cycle of the Trump era, the war between the Saudi Arabia-led coalition and an alliance of local factions in Yemen continues apace. The conflict has caused thousands of civilian deaths, forced millions of people to flee their homes, and pushed the country to the brink of famine, all part of what UN agencies have described as a catastrophic situation.

The United States has played a large role in this war, providing weapons, intelligence, targeting expertise, and logistical support to the Saudi-led coalition that has been accused of aggravating the humanitarian disaster with airstrikes that have killed hundreds of civilians and a blockade that has restricted the flow of vital supplies available to Yemen’s population.

A January 26, 2018 report by the United Nations Panel of Experts on Yemen declared that, “[a]fter nearly three years of conflict, Yemen, as a State, has all but ceased to exist.”  The report went on to document many violations of international humanitarian law (IHL, also known as the law of armed conflict) and human rights law, including ten air strikes by the Saudi-led coalition in 2017 leading to at least 157 fatalities and 135 injuries. The panel found that even if in some of these cases, the Saudi Arabia-led coalition had targeted legitimate military objectives, “it is highly unlikely that the international humanitarian law principles of proportionality and precautions in attack were respected.”

All of this raises serious questions about the U.S.’s involvement in the war and the resulting humanitarian disaster. With that in mind, we are launching a series of articles exploring the legal issues surrounding U.S. support for the Saudi-led coalition in Yemen. This first piece will provide background information on the conflict, its key players, and U.S. military support.

Subsequent articles will focus on U.S. domestic law, beginning in Part 2 with the War Powers Resolution. Part 3 will examine the Arms Export Control Act. Part 4 will look at aiding and abetting violations of the War Crimes Act. Part 5 will consider the Alien Tort Statute. The articles will then shift focus to international law, beginning in Part 6 with the question of whether the United States is a party to the armed conflict in Yemen. Part 7 will look at whether U.S. support violates Article 2(4) of the UN Charter. Part 8 will analyze Article 16 of the ILC Draft Articles on State Responsibility. Finally, Part 9 will look at due diligence obligations under Common Article 1 of the 1949 Geneva Conventions.

The final article will coincide with the release of a report by the Yale Law School Center for Global Legal Challenges on the issues covered in the posts, as well as a conference to be held at Yale Law School on April 13.

The Houthi-Saleh Alliance and Civil War in Yemen

The primary insurgent group in Yemen, and the primary target of the Saudi-led coalition, are known as the Houthis. The Houthis are a predominantly Zaydi Shi’a Islamic religious-political-armed movement founded in northern Yemen in the late 1990s in the northwestern province of Sa’da by Hussein Badreddin al-Houthi. In 2004, the Saleh government sent forces into Sa’da to put down protests led by al-Houthi. After several months of battles between government forces and Houthi’s followers, government forces killed al-Houthi. The Houthi movement took his name after his death.  It is widely believed that Iran provides some support to the Houthis, and Saudi Arabia claims that the Houthis are an Iranian proxy, but the level of support provided by Iran and level of influence it enjoys over the Houthis is contested.

The central government of Yemen began to unravel after the 2011 Arab Spring protests.  Former Yemeni President Ali Abdullah Saleh agreed to step down at the end of 2011, in exchange for a promise of immunity from prosecution. Saleh was replaced by his Vice President, Abdu Rabbu Mansour Hadi. The transition agreement under which Hadi took power stipulated that Hadi would form a national unity government, comprised of members of the incumbent ruling party and the Yemeni opposition. The effort to form a unity government failed in January 2014, and the Houthis launched a military offensive against tribal allies of President Hadi.

Shortly after beginning their attacks against President Hadi’s allies, the Houthis were joined by forces loyal to Saleh in a temporary alliance against Hadi. The Houthi-Saleh forces seized the Yemeni capital, Sana’a, in 2014 and placed Hadi under house arrest in early 2015. Hadi escaped to the city of Aden, and eventually fled to Saudi Arabia before Aden fell to the Houthis.

On March 24, 2015, President Hadi requested assistance from Saudi Arabia, the United Arab Emirates, Bahrain, Oman, Kuwait, and Qatar. These countries responded by forming a Saudi-led coalition that provided air support to a patchwork of Yemeni ground forces loyal to Hadi, consisting of military units, tribal militias, and Islamic militants. The Saudi-led coalition was successful in retaking the southern port city of Aden and other traditionally Sunni areas in southern Yemen. Houthi-Saleh forces retained control of western Yemen. UN Special Envoy Ismail Ould Cheikh Ahmed, appointed in April 2015 by UN Secretary-General Ban Ki-moon, attempted to reach a negotiated settlement, but failed to get the two sides to reach agreement on even a basic framework for peace.

In December 2017, the Houthi-Saleh alliance fell apart after Saleh unexpectedly announced he was open to dialogue with the Saudi-led coalition. Days later, Houthi fighters killed Saleh. Despite the collapse of the Houthi-Saleh alliance, it is expected that the war in Yemen will continue.

The Saudi Coalition and Civilian Casualties

Since the beginning of its involvement, the Saudi-led coalition has come under intense scrutiny for killing civilians and destroying civilian infrastructure with its airstrikes. The United Nations Panel of Experts on Yemen has published four annual reports documenting numerous violations of human rights, IHL, and other international law provisions by all parties in Yemen. In its most recent report, the panel documented ten cases of coalition airstrikes that it concluded violated IHL:

  • On March 16, 2017, a helicopter fired at a Somali migrant boat in the Red Sea, killing 42 civilians and injuring 34.
  • On June 9, 2017, a strike on a residential building in Sana’a killed 4 civilians and injured 8.
  • On August 4, 2017, a strike on a residential building in Sa’dah killed 9 civilians and injured 3.
  • On August 23, 2017, a strike on a motel in Arhab killed 33 civilians and injured 25.
  • On August 25, 2017, a strike on a residential building in Sana’a killed 16 civilians and injured 17.
  • On September 2, 2017, a strike on a residential building in Hajjah killed 3 civilians and injured 13.
  • On September 16, 2017, a strike on a vehicle in Ma’rib killed 12 civilians.
  • On November 1, 2017, a strike on a market in Sa’dah killed 31 civilians and injured 26.
  • On November 10, 2017, a strike on a residential building in Sa’dah killed 4 civilians and injured 4.
  • On November 14, 2017, a friendly fire strike against President Hadi’s military forces in Ta’izz resulted in the 3 civilian deaths and 5 injuries.

U.S. Military Involvement

Airstrikes and Limited Ground Operations

Since 2011, the United States has conducted extensive military operations in Yemen, including against al-Qaeda in the Arabian Peninsula (AQAP) and, more recently, against the Islamic State. The Obama Administration relied on Congress’s 2001 Authorization for the Use of Military Force (AUMF) against groups responsible for the 9/11 attacks to justify military actions against AQAP, arguing that the group is considered to be “part of, or at least an associated force of,” al-Qaeda. The 2001 AUMF has also been used to justify U.S. actions against ISIS in Yemen. This position is the subject of ongoing legal controversy. Despite this controversy, the United States maintains its stance that actions against ISIS are authorized by the 2001 AUMF.

The United States conducted a total of 157 airstrikes in Yemen from 2011 through 2016. U.S. strikes increased dramatically in 2017, the first year of the Trump Administration. By September 2017, U.S. Central Command stopped issuing updated statements for individual strikes and simply estimated that it had conducted over 100 strikes. In late December 2017, the Department of Defense acknowledged “multiple ground operations and more than 120 strikes in 2017.” Meanwhile, unverified news reports suggest the annual total reached 131.  Most of the 2017 airstrikes were against AQAP, though at least three in 2017 were against the Islamic State.

The United States has also conducted ground raids in Yemen using Special Operations forces in pursuit of suspected terrorist targets. The precise scope of these raids is not public, but one raid against AQAP—the first commando raid authorized by President Trump—led to the death of a Navy Seal, Chief Petty Officer William “Ryan” Owens.  The operation that killed Owens also led to the death of a number of civilians, including children, leading Yemen to withdraw permission for ground missions in February 2017.

Attacks on U.S. Navy Ships and Response

The United States has not taken direct military action against the Houthis (who are not covered by existing congressional authorizations for the use of force), except in one response to direct attack. In October 2016, on three separate occasions, Houthi-Saleh forces launched anti-ship cruise missiles against U.S. Navy ships patrolling off the coast of Yemen. The strikes may have been in response to the recent Saudi-led bombing of a funeral in Sana’a, in which a number of civilians were killed. On October 14, 2016, President Obama notified Congress in a letter to the Speaker of the House and the President Pro Tempore of the Senate that the U.S. Armed Forces had taken missile strikes against radar facilities in Houthi-controlled territory. The letter described the actions as “limited and proportionate” acts of self-defense pursuant to President Obama’s constitutional authority.  President Obama also referenced the strikes in his six-month periodic update to Congress on December 5, 2016, pursuant to the War Powers Resolution.

Since assuming office, President Trump has sent three letters to Congress pursuant to the War Powers Resolution. The first discussed the April 6 strike on Syria’s military airfield and the second was a six-month periodic report on worldwide operations. Neither report mentioned any further military activity against the Houthi-Saleh alliance. The third letter mentioned that the United States, “in a non-combat role,” “continued to provide logistics and other support” to anti-Houthi forces in Yemen.

U.S. Military Assistance

On March 25, 2015, the United States announced that it would provide “logistical and intelligence support” to the Saudi-led coalition forces against the Houthis. Since then, U.S. military assistance to the Saudi-led coalition against the Houthi alliance has been in the form of weapons sales, training, and mid-air refueling. The refueling operations involved a U.S. tanker refueling coalition aircraft outside of Yemen’s airspace at least once a day. Intelligence sharing involved embedding a joint coordination planning cell in Saudi Arabia’s operations center in Riyadh. According to defense officials at the outset of U.S. assistance, the United States would not provide targeting information to the Saudis, but would review Saudi-picked targets and advise on the risk of civilian casualties. In August 2016, the United States withdrew U.S. military personnel from Saudi Arabia who had been coordinating with the Yemen campaign.

In May 2016, the United States provided support to efforts by the Yemeni military and the UAE to retake the port city of Mukalla from AQAP. The American amphibious assault ship USS Boxer positioned itself off the cost of Yemen and provided medical support to UAE troops. In addition, a Pentagon spokesman revealed that the U.S. military had deployed a “small number” of troops on the ground in Yemen to provide intelligence and logistical assistance, including “advice and assistance with operational planning, maritime interdiction and security operations, medical support and aerial refueling.”

A year into the war between the Saudi coalition and Houthi-Saleh alliance, members of Congress expressed growing concern about civilian casualties. Several resolutions were considered to reign in or place conditions on military assistance to Saudi Arabia in an effort to curb civilian casualties, including halting the sale of cluster munitions (S. 2943), but these proposals were ultimately rejected. However, political circumstances changed in October 2016, following  Houthi-Saleh missile attacks against U.S. forces conducted in possible retaliation for the bombing of a funeral in Sana’a that killed 140 people. The Obama Administration announced its intention to review U.S. military assistance to the Saudi-led coalition. In December 2016, the Obama Administration cancelled the planned sale of 16,000 precision-guided munitions (valued at $350-$390 million) and announced that it would restrict further intelligence sharing involving targeting of Houthi-Saleh forces. At the same time, the United States announced it would continue its refueling operations and would step up its training of the Saudi Air Force, as well as continue intelligence sharing in regards to AQAP and securing the Saudi-Yemeni border.

After President Trump took office in early 2017, U.S. foreign policy reversed many of President Obama’s restrictions on support for the Saudi operations in Yemen. During his visit to Riyadh, President Trump announced his intent to sell $110 billion in arms to Saudi Arabia. In June 2017, a move by Senators concerned about civilian deaths to prevent the sale of $500 million in precision-guided munitions was narrowly defeated 53-47. In order to help gain approval for the weapons sale, Saudi Foreign Minister Adel al-Jubeir wrote a letter to U.S. Secretary of State Rex Tillerson promising to exercise greater caution to avoid civilian casualties. To help it fulfill this promise, the U.S. military agreed to provide the Saudi military with a $750 million training program that included lessons on avoiding civilian casualties in airstrikes. Saudi Arabia also promised that it would expand its list of off-limits targets and strictly adhere to that list. Last, the U.S. targeting cell that had previously worked in Riyadh would return and be given greater access to Saudi operations, working in the air operations control center itself rather than a separate office. Sen. Mark Warner (D-Va.), who was among the five Democrats who voted for the plan, mentioned the need for more training of the Saudi military as his reason for approving the arms sale.

Since the Senate vote, however, the record of the Saudi-led coalition has not been promising. As documented by the UN Panel of Experts January 2018 report, a number of attacks since the vote have killed civilians. In addition, in December 2017, two separate Saudi airstrikes—one on a market in Taiz province and another on a farm in Hudaydah province—killed 68 civilians in one day.

Faced with a growing humanitarian crisis in December 2017, President Trump called on Saudi Arabia to end its blockade of Yemen and allow aid to reach civilians. The Saudi-led coalition recently committed $1.5 billion in aid to Yemen and promised to set up regular humanitarian aid flights and establish 17 “safe passage corridors” for overland transportation of aid. These promises, however, like previous ones by Saudi Arabia, have been met with criticism for failing to make any substantial difference in helping Yemen’s civilian population.

The next eight posts in this series will address the many complex domestic and international legal issues raised by these facts.

(Spencer Platt/Getty Images)