In February 2018, Senators Sanders, Lee, and Murphy introduced S.J.Res. 54, a joint resolution that would direct the President to remove U.S. forces from "hostilities in or affecting" Yemen (except for those U.S. forces engaged in counterterrorism operations directed at al Qaeda or associated forces). Since March 2015, the U.S. military has supported military operations in Yemen by a coalition of countries led by the kingdom of Saudi Arabia (KSA). The coalition operations, including airstrikes, have supported a broader campaign to reinstate the internationally recognized government of Yemeni President Abdu Rabbu Mansour Hadi. Hadi was ousted by force in early 2015 by the Ansar Allah/Houthi movement and loyalists of the previous president of Yemen, the late Ali Abdullah Saleh. Since 2015, some lawmakers have argued that U.S. support to the Saudi-led coalition makes the United States a party to the armed conflict.
The sponsors of S.J.Res. 54 note that the House of Representatives in November 2017 adopted H.Res. 599, which states in its introductory clauses that Congress has not authorized the use of force against parties participating in Yemen's civil war who are not subject to other authorizations for the use of military force. The sponsors of S.J.Res. 54 further argue that by providing support to the Saudi-led coalition, U.S. forces have been introduced into a "situation where imminent involvement in hostilities is clearly indicated" based on the criteria of the War Powers Resolution (50 U.S.C Ch. 33). The Trump Administration disagrees.
On March 20, Senator Bernie Sanders moved to discharge the Senate Foreign Relations Committee from further consideration of S.J.Res. 54 pursuant to expedited procedures referenced in 50 U.S.C. 1546a. These measures make any joint resolution or bill directing the withdrawal of U.S. forces from hostilities eligible for the procedures outlined in Section 601(b) of the International Security Assistance and Arms Export Control Act of 1976 (P.L. 94-329). After four hours of debate, the Senate later voted to table this motion to discharge (55-44). During the debate, the Senate Foreign Relations Committee Chairman Senator Bob Corker described plans to hold a committee hearing on Yemen and to consider Yemen-related legislation and broader authorization for the use of military force legislation in committee. A proposed joint resolution offered by Senators Todd Young and Jeanne Shaheen (S.J.Res. 55) would create a certification mechanism to allow the conditional continuation of some U.S. military support to some operations in Yemen.
As of February 27, 2018, according to a Department of Defense letter to Senate leaders, "the United States provides the KSA-led coalition defense articles and services, including air-to-air refueling; certain intelligence support; and military advice, including advice regarding compliance with the law of armed conflict and best practices for reducing the risk of civilian casualties." After a policy review in 2017, President Trump directed the Administration "to focus on ending the war and avoiding a regional conflict, mitigating the humanitarian crisis, and defending Saudi Arabia's territorial integrity and commerce in the Red Sea." The department argues that "the limited military and intelligence support that the United States is providing to the KSA-led coalition does not involve any introduction of U.S. forces into hostilities for purposes of the War Powers Resolution."
The U.S. military provides in-flight refueling to the militaries of Saudi Arabia and the United Arab Emirates (UAE) pursuant to bilateral Acquisition and Cross Servicing Agreements (ACSAs). The agreements provide for reciprocal logistical support under a variety of circumstances, and their underlying statutory authority does not prohibit U.S. support to partner forces engaged in armed conflict.
Congressional debate over U.S. support to the Saudi-led coalition's military operations since 2015 has been driven by reports of Yemeni civilian casualties resulting from the coalition's operations and broader concerns about deteriorating humanitarian conditions, restrictions on the flow of goods and humanitarian aid, the war-driven empowerment of Al Qaeda and Islamic State forces, and Iranian support for the Houthis. Some lawmakers have suggested that U.S. arms sales and military support to the coalition have enabled alleged violations of international humanitarian law, while others have argued that U.S. support to the coalition improves its effectiveness and helps minimize civilian casualties. Congress has considered but has not enacted proposals to curtail or condition U.S. defense sales to Saudi Arabia or to prohibit the use of funds for coalition support operations.
Saudi officials acknowledge that some of their operations have caused undesired civilian casualties, while maintaining that their military campaign is an act of legitimate self-defense because of their Yemeni adversaries' repeated, deadly cross-border attacks, including ballistic missile attacks. After a Houthi-fired missile with alleged Iranian origins landed deep inside Saudi Arabia in November 2017, the coalition instituted a full blockade of all of Yemen's ports, exacerbating the country's humanitarian crisis. The Trump Administration demanded that the Saudi-led coalition ease the port restrictions, while condemning Iran's reported involvement in missile transfers and launches.
Since December 2017, Saudi Arabia has temporarily eased the blockade and taken some steps intended to improve humanitarian access and conditions in Yemen. The Trump Administration has welcomed these steps and continues to support a negotiated settlement to Yemen's civil war. The U.S. intelligence community reported to Congress in February 2018 that Yemen's conflict is "likely to continue for the foreseeable future," and "continued fighting almost certainly will worsen the vast humanitarian crisis."
There is disagreement as to whether U.S. forces assisting the Saudi-led coalition have been introduced into active or imminent hostilities for purposes of the War Powers Resolution. S.J.Res. 54 asserts that U.S. Armed Forces currently "command, coordinate, participate in the movement of, or accompany" coalition forces, forces which are engaged in active hostilities, and therefore U.S. forces have been introduced into hostilities. The Department of Defense argues that U.S. forces do not engage in such activities alongside coalition forces conducting "counter-Houthi operations," and that U.S. Armed Forces are not engaged in hostilities because no "U.S. armed forces are actively engaged in exchanges of fire with opposing units of hostile forces."
This definitional dispute hinges on the proximity in time and distance of U.S. forces to coalition forces when such forces are exchanging fire with Houthi forces, and whether U.S. forces are involved in exchanging such fire. These definitions have long eluded inter-branch agreement, and it is not clear what effect on U.S. military activities S.J.Res. 54 (if enacted, likely after overcoming presidential veto) would have. Any interpretation of these terms that becomes law might have significant ramifications for the use of the U.S. military to assist allied countries engaged in armed conflict.