In his first major foreign policy speech since taking office, President Biden announced the United States will end support for “offensive operations” in Yemen’s war. The Feb. 4 statement marks a significant victory for a coalition of progressive and conservative policymakers and organizers who have fought to end U.S. involvement in the war. While not an unexpected development, given Biden’s campaign promises to end U.S. support for Yemen’s war, this announcement represents a significant shift in the American position since U.S. involvement began in 2015 under the Obama administration.

After more than five years of fighting, Yemen faces the largest humanitarian crisis in the world, with 80 percent of the population in need of aid, according to United Nations statements. A combination of shortfalls in international aid and obstruction by armed groups has impeded Yemenis from accessing lifesaving humanitarian aid. Ending U.S. support for the coalition is critical, but it is just a first step toward ending the war and addressing the humanitarian crisis.

How did the U.S. get involved in Yemen’s civil war?

Yemen’s government fled the capital of Sanaa after the Houthis took it over in September 2014. In March 2015, the internationally recognized government invited a coalition of nine Arab countries to launch a military intervention to counter the Houthi rebellion and restore the government to power. The Saudi-led intervention included a campaign of airstrikes, the blockade of air and sea routes into Yemen and the deployment of troops to train and assist local proxy forces.

From the beginning of the coalition’s intervention, the United States provided logistical and intelligence support. The U.S. initially provided aerial refueling for the coalition’s air campaign — a campaign analysts estimate was responsible for more than 8,000 civilian casualties between 2015 and late 2019. U.S. military personnel also provided intelligence and targeting advice, including technical instruction and a “no-strike list” of civilian infrastructure, although American officials maintain the U.S. did not participate in target selection.

In addition to direct logistical support for operations in Yemen, the U.S. also continued to supply Saudi Arabia and the UAE with arms-sale packages. Theoretically, these weapons could have been used in Yemen, although there is typically a gap of several years between the finalization of a weapons sale and delivery.

These sales demonstrated continuing U.S. support for the coalition, however. By the end of the Obama administration, the U.S. had finalized agreements for more than $115 billion in weapons and support for Saudi Arabia, while the Trump administration added around $25 billion in sales in four years. The Trump administration’s insistence on selling weapons to Saudi Arabia, despite significant congressional opposition, as part of broader efforts to bolster the U.S.-Saudi relationship signaled continued U.S. support for the intervention in Yemen.

What does ending U.S. support mean?

The Biden administration has provided few details about what this announcement will mean in practice. The U.S. had already ended the aerial refueling in late 2018, after the murder of journalist Jamal Khashoggi by Saudi security officers triggered a public outcry. A Pentagon spokesperson clarified on Friday that all noncombat assistance to the coalition’s operations, including “intelligence and some advice and best practices … has been terminated.”

Biden also promised to end “relevant arms sales,” but it’s not entirely clear which sales are included. In its final months, the Trump administration attempted to rush through several weapons deals, including a $290 million sale of precision-guided bombs and related materials to Saudi Arabia. The Biden administration will reportedly pause this and another Saudi deal involving precision-guided weapons. But other recent sales, notably the planned sale of F-35s to the UAE, are more ambiguous, as the UAE drew down most of its forces in Yemen in the summer of 2019, although it still remains involved in the conflict through its local partners.

In his State Department speech, Biden also pledged to “help Saudi Arabia defend its sovereignty and its territorial integrity,” a strong suggestion that other arms sales and forms of security assistance will continue in some form. The United States also provides military training and deploys military personnel and hardware to Saudi Arabia — and frames this assistance as defensive measures. The administration clarified that the announcement does not include operations against al-Qaeda in the Arabian Peninsula and ISIS.

What happens now?

The announcement that the U.S. will stop supporting the coalition was a significant one — but other news from the speech may be equally important. Biden also promised to step “up our diplomacy to end the war in Yemen,” announcing the appointment of an envoy for Yemen, support for a cease-fire and the U.N.-led peace process, and a commitment to ensuring humanitarian aid reaches the Yemeni people. This indicates the administration plans to make a sustained investment in diplomacy to end Yemen’s war. The acknowledgment that Yemen’s war is “unwinnable” — and a conflict best addressed through diplomacy — is a major pivot in U.S. policy.

The State Department also said it would revoke the Trump administration’s last-minute designation of the Houthis as a Foreign Terrorist Organization, a decision an official clarified “is due entirely to the humanitarian consequences” of the designation. The U.N. and humanitarian organizations had warned that the designation could prevent humanitarian aid from reaching people in dire need.

The U.S. investment in diplomacy will be critical because ending American support for the coalition’s intervention won’t end the war in Yemen. The conflict is localized and began with local armed groups competing for access to governance. Ending this conflict depends on the decisions of local Yemeni groups — and whether and how they are included in peace negotiations.

My research on civil wars also suggests the United States can play a critical role in overseeing the peace process, especially by exerting leverage over its Gulf security partners to come to and abide by the terms of a peace settlement. This diplomatic support will be important to ending the civil war in Yemen.

Alexandra Stark (@alexmstark) is a senior researcher at New America.