The Legality of U.S. Support for the Saudi-Led Campaign in Yemen

[Editor’s Note: This is the second piece in our Yemen Crisis Forum. Readers may be interested in the first piece in the Forum, “The Yemen Crisis and the Law: The Saudi-Led Campaign and U.S. Involvement.”]

Yesterday, Senator Bernie Sanders (D-Vt.) introduced a joint resolution, co-sponsored by Senators Mike Lee (R-Ut.) and Chris Murphy (D-Ct.), calling for the removal of U.S. armed forces from hostilities in the Republic of Yemen that have not been authorized by Congress.

Shortly after the resolution became public, a letter from the Acting General Counsel of the Department of Defense, William Castle, was released. In the letter, Castle argued that the premise of the proposed resolution was “flawed” because it incorrectly asserts the U.S. forces have been introduced into “hostilities.”

This exchange brings new attention to an issue that has been simmering below the surface for months: the legality of the U.S. support for the Saudi-led coalition in Yemen under the War Powers Resolution (WPR)—the primary law governing the deployment of U.S. military forces.  Indeed, the joint resolution introduced by Sen. Sanders is the latest in a series of legislative efforts to reign in U.S. military support for the Saudi-led coalition in Yemen.

To assess the charge that recent U.S. actions in Yemen violate the War Powers Resolution—and the Department of Defense’s response that it does not—it is necessary to undertake a careful examination of publicly available information about U.S. involvement in Yemen.  As noted in our first article in this series, American forces are involved in the conflict Yemen in three separate capacities: (1) U.S. Navy ships are located off the coast of Yemen; (2) U.S. forces have conducted operations against al Qaeda’s Yemen branch, known as al Qaeda in the Arabian Peninsula, or AQAP; (3) the U.S. military has provided assistance to Saudi-led operations, including through mid-air refueling of Saudi-led coalition aircraft and providing other support, such as targeting advisers.

We examine each of these in turn and conclude that U.S. military forces have not crossed the threshold of direct, imminent involvement in hostilities, under traditional interpretations of the War Powers Resolution. However, members of Congress have advanced a novel interpretation of Section 8(c), arguing that the War Powers Resolution also encompasses indirect involvement in hostilities though support of foreign military forces. This argument has merit, although it rests on an expansive interpretation of the War Powers Resolution, which could have implications for U.S. security assistance around the world.  Moreover, the Department of Defense response appears to refute the argument on factual grounds, though significant unanswered questions remain.

(1) U.S. Navy ships off the coast of Yemen

The War Powers Resolution states that, under the President’s constitutional powers as Commander in Chief, the President can introduce armed forces into “hostilities” or into “situations where imminent involvement in hostilities is clearly indicated by the circumstances” only pursuant to: “(1) a declaration of war, (2) specific statutory authorization, or (3) a national emergency created by attack upon the United States, its territories or possessions, or its armed forces.” The presence of U.S. Navy ships off the coast of Yemen has not been specifically authorized by Congress and therefore prompts the question of whether their presence introduces American forces into a situation where “imminent involvement in hostilities is clearly indicated by the circumstances.” If so, the President would be required to submit a report to Congress within 48 hours of introducing armed forces (which he has not done). And within 60 days after submitting a report (or of being required to submit a report), he would be required to terminate the use of armed forces.

The President has the authority to deploy combat-ready U.S. forces “into the territory, airspace, or waters of a foreign nation” without prior congressional approval, as long the military personnel are not at imminent risk of hostilities.  The Department of Justice’s Office of Legal Counsel has concluded that the President’s power to deploy U.S. armed forces around the world is unfettered. As the individual who “is exclusively responsible for the conduct of diplomatic and foreign affairs,” the President may, “absent specific legislative restriction, deploy United States armed forces abroad or to any particular region.”  Therefore, the mere deployment of U.S. Navy ships to the region does not trigger the War Powers Resolution, absent evidence that they have been introduced into hostilities or imminent hostilities.

U.S. Navy ships came under attack by Houthi-Saleh forces in three separate missiles strikes in October 2016.  The ships were in international waters when they were attacked.  The United States responded on October 14, 2016, by launching a missile strike against the Houthi-Saleh-controlled radar stations.  President Obama reported the action in a letter to Congress, consistent with the War Powers Resolution.  Since the military action was taken as a short term, limited emergency response to an attack upon U.S. armed forces, and was promptly reported to Congress, that was sufficient to conform to the Resolution’s requirements.

Because the threat appears to have been addressed, the deployment of U.S. Navy ships off the coast of Yemen does not entail deployment into hostilities or into a situation where hostilities are imminent.  The failed missile strikes on U.S. Navy ships are the only direct attacks on U.S. forces by the Houthi-Saleh alliance during the nearly three-year war by the Saudi-led coalition.  Since the U.S. response to those attacks, there have been no further attacks on U.S. forces.  The anti-ship cruise missile launchers used to attack U.S. ships appear to have been destroyed.  Given this record, the risk of hostilities does not rise to the level of “imminent.” If the risk were to rise, however, that would strengthen the case that hostilities are imminent, a report to Congress required, and the 60-day clock initiated.

Acting General Counsel Castle’s letter comes to the right conclusion, but asserts far greater authority than necessary—or warranted.  It argues that the October 2016 strikes against radar facilities in Houthi-controlled territory in defense of U.S. Navy ships were justified under Article II.  That is clearly right, given the limited scope of the operation.  But he further asserts that, “The President has authority pursuant to Article II to take military action that furthers sufficiently important national interests.” Such a blanket claim goes much further than the recognized scope of the President’s constitutional war powers.

(2) Operations Against AQAP and ISIS in Yemen

The U.S. has acknowledged conducting operations against AQAP and ISIS in Yemen.  In May 2016, for example, the Pentagon admitted that a small contingent of U.S. military personnel was stationed on the ground in Yemen, supporting UAE efforts to retake the Yemeni port city of Mukalla from AQAP.  Although the United States was supporting a member of the Saudi-led coalition, the target of these efforts was AQAP, not the Houthis.

The United States has consistently taken the position that operations against al Qaeda and its affiliates, including AQAP and ISIS, are covered by the 2001 Authorization for the Use of Military Force.  There are real concerns that the 2001 statute, passed by Congress days after the 9/11 attacks on the World Trade Center, and authorizing force against those affiliated with the attacks, cannot be properly applied to operations more than fifteen years later to a group and in a country with no direct involvement in those attacks.  Nonetheless, the Unites States’ consistent position that the 2001 AUMF applies to U.S. operations against AQAP has been met with relatively little challenge.  If, therefore, the ground operations have been and remain limited to operations against AQAP, many would accept that they are covered under the 2001 AUMF. If they are covered by prior statutory authorization, then—under the terms of the War Powers Resolution—that would satisfy the need for Congressional authorization.

Acting General Counsel Castle’s letter to Senate Majority Leader McConnell does raise a question about the 2001 AUMF authority. The Senate joint resolution “directs the President to remove United States Armed Forces from hostilities in or affecting the Republic of Yemen, except United States Armed Forces engaged in operations directed at al Qaeda or associated forces . . . .”  Castle states in response that, pursuant to the 2001 AUMF, “U.S. armed forces are currently engaged in hostilities against both al Qa’ida in the Arabian Peninsula (AQAP) and the Islamic State of Iraq and Syria in Yemen. Hostilities against AQAP and associated forces are explicitly exempted from the resolution’s termination requirement, but hostilities against ISIS are not similarly exempted.”  This suggests that ISIS is not an associated force of al Qaeda.  That appears to be in some tension with earlier explanations of the legal basis for military operations against ISIS, which emphasized the historic ties between al Qaeda and ISIS to make the case that ISIS properly fell within the AUMF’s scope.  This response raises new questions about the legal basis under which the Trump Administration understands itself to be operating against ISIS.

(3) Mid-air Refueling of Saudi-led Coalition Aircraft and Other Support

At the outset of U.S. support for the Saudi-led coalition, the Pentagon stated that all mid-air refueling missions would be conducted outside of Yemeni airspace.  Assuming that the U.S. military has adhered to this policy for its troops supporting the Saudi coalition, including the tanker aircrews (and there is no indication that they have not), it is difficult to argue that military personnel are at imminent risk of hostilities.  Military personnel who are providing targeting assistance and advice to the coalition have been stationed in Riyadh and Bahrain, far from the battlefield and the imminent risk of being caught up in direct hostilities.

However, a little-noticed provision of the War Powers Resolution, Section 8(c), provides that, “For purposes of this joint resolution, the term ‘introduction of United States Armed Forces’ includes the assignment of members of such armed forces to command, coordinate, participate in the movement of, or accompany the regular or irregular military forces of any foreign country or government when such military forces are engaged, or there exists an imminent threat that such forces will become engaged, in hostilities.”  The plain meaning of this provision appears to be that when the U.S. armed forces are assigned to “command, coordinate, participate in the movement of, or accompany” foreign forces that are engaged in hostilities, such as the Saudi-led coalition, that constitutes the “introduction of U.S. Armed forces.”

This provision was highlighted by Congressmen Ro Khanna (D-Calif.), Mark Pocan (D-Wisc.), and Walter Jones (R-NC), who introduced the first resolution in the House, in September 2017, that invoked the War Powers Resolution to order President Donald Trump to remove U.S. military forces supporting the Saudi-led war against the Houthi-Saleh alliance in Yemen. In a subsequent New York Times op-ed, the three lawmakers reiterated their argument that U.S. support for the Saudi-led coalition constituted a war that required authorization by Congress, specifically invoking the language of Section 8(c).

There have been few interpretations of Section 8(c), making it difficult to assess the congressmen’s claims that the current U.S. support for the Saudi coalition runs afoul of it.  In his testimony before the Senate Foreign Relations Committee on June 28, 2011 regarding U.S. operations in Libya, then-Legal Adviser Harold Koh argued in a footnote that the section gives rise to “a duty of Congressional notification, but not termination.” Section 8(c) is textually linked, he explained, through the term “introduction of United States Armed Forces” not to the “hostilities” language that triggers the termination requirement, but instead to a different clause that triggers a reporting requirement.

In his February 27 letter to Senate Majority Leader McConnell, Acting General Counsel Castle offers a different interpretation of Section 8(c).  He argues that the relevant question is “whether U.S. forces—not the foreign forces they are accompanying—are introduced into hostilities or situations involving the imminent threat thereof.”  Though Castle’s letter does not rely on it, the State Department came to a similar conclusion in 1981 when considering whether the section applied to U.S. military advisers in El Salvador. It concluded that Section 8(c) was not intended to require a report when U.S. military personnel might be involved in training foreign military personnel, if there were no imminent involvement of U.S. personnel in hostilities.  The military personnel in El Salvador “will not act as combat advisors, and will not accompany Salvadoran forces in combat, on operational patrols, or in any other situation where combat is likely.”

Both Koh’s and Castle’s readings are difficult to square with the plain language of the Resolution.  As noted above, the provision states that when the U.S. armed forces are assigned to “command, coordinate, participate in the movement of, or accompany” foreign forces that are engaged in hostilities, such as the Saudi-led coalition, that constitutes the “introduction of U.S. Armed forces,” which, under Section 2 of the War Powers Resolution, the President is not authorized to do absent declaration of war, statutory authorization, or national emergency.

These readings are also in some tension with the limited legislative history of Section 8(c). At the time of the adoption of the Resolution, the Senate report stated that the purpose of Section 8(c) was “to prevent secret, unauthorized military support activities and to prevent a repetition of many of the most controversial and regrettable actions in Indochina. The ever-deepening ground combat involvement of the United States in South Vietnam began with the assignment of U.S. ‘advisers’ to accompany South Vietnamese units on combat patrols; and in Laos, secretly and without congressional authorization, U.S. ‘advisers’ were deeply engaged in the war in northern Laos.” For 8(c) to serve the purpose of avoiding a repetition of such actions, it would seem to require more than mere reporting to Congress and to apply to situations where U.S. troops are acting as “advisers” to foreign troops involved in hostilities, even when those U.S. troops themselves are not involved in hostilities.

The obvious difficulty with the plain meaning interpretation of Section 8(c) is that it suggests that the United States violates the War Powers Resolution when it provides assistance to a foreign military involved in hostilities. As Jack Goldsmith has pointed out, this interpretation “implies that the assignment of one or two U.S. military aides to a foreign military effort triggers the WPR.”  This would arguably lead to what Koh called “absurd results” where the War Powers Resolution’s 60-day clock would “require termination of the ‘assignment’ of even a single member of the U.S. military to assist a foreign government force, unless Congress passed legislation to authorize that one-person assignment.”

It may be not be necessary to resolve the debate over the proper scope of Section 8(c) in order to resolve the question of whether U.S. assistance to the Saudi-led coalition constitutes “hostilities” under the War Powers Resolution.  The letter from Acting General Counsel Castle states that, “With respect to U.S. support to the [Saudi]-led coalition, U.S. forces do not currently command, coordinate, accompany, or participate in the movement of coalition forces in counter-Houthi operations. Thus, no U.S. forces are accompanying the [Saudi]-led coalition when its military forces are engaged, or an imminent threat exists that they will become engaged, in hostilities.”

The letter, which is unclassified, offers no facts to support this claim.  But assuming that it is accurate, that would seem to settle the matter.  Follow up questions, however, would be appropriate, including whether refueling or targeting assistance has been provided to the Saudi-led coalition in its operations against the Houthis. The letter from Castle later references “U.S. participation in a Joint Combined Planning Cell with the [Saudi government] and mid-air refueling of [Saudi]-led coalition aircraft.” It is not clear from the letter whether the Department regards such participation as constituting “participat[ing] in the movement of coalition forces in counter-Houthi operations.”  If it does not, then it would be reasonable to ask whether the Department is correct to conclude that such assistance does not constitute “participat[ion] in the movement of” such forces, implicating Section 8(c).  If refueling enables the Saudi coalition to move the forces that are operating in Yemen, it would be reasonable to conclude that the U.S. armed forces are thereby participating in those forces’ movement.

There is a related concern that the United States, by supporting the Saudi-led coalition, could be described a co-belligerent in the conflict between the Saudi-led coalition and the Houthis. If so, that might trigger the WPR’s prohibition on involving U.S. armed forces in “hostilities” or “imminent hostilities.” After all, as Nathalie Weizmann has argued, if the United States enters the conflict, it could be seen as a belligerent in the conflict.

The precise intended scope of Section 8(c) is surprisingly underdeveloped, given the extent of U.S. military assistance and advice in many parts of the world.  Adopting the expansive definition of Section 8(c) advocated by several members of Congress could provoke a reassessment of a number of ongoing U.S. military advising missions around the world. It is therefore important to proceed with caution in interpreting the scope of this provision. To assess whether U.S. support to the Saudi-led coalition in Yemen implicates Section 8(c) would likely require, at a minimum, more information than is publicly available about the nature and scope of these activities.

Last, Acting General Counsel Castle’s letter asserts in footnote 3 that, “Because the President has directed U.S. troops to support the KSA [Kingdom of Saudi Arabia] operations pursuant to his authority under Article II, and because the limited operation does not implicated [sic] Congress’s constitutional authority to Declare War, the draft resolution would raise serious constitutional concerns to the extent it seeks to override the President’s determination as Commander in Chief.” This is an astonishing assertion. It suggests that the acting General Counsel of the Department of Defense believes that the President might be constitutionally entitled to disregard a joint resolution of Congress ordering the President to cease support to the Saudi-led coalition and continue those operations with his authority at its lowest ebb.  This, perhaps more than any other statement in the letter, should prompt follow up from members of Congress.

At least one thing is clear: the members of Congress have raised important questions about the legality of the support for the Saudi-led coalition that are, as yet, not settled by the Administration’s response—and, indeed, that response may raise more questions than it answers.

Image: Royal Saudi Air Force Eurofighter EF-2000 Typhoons have played a critical role in the Saudi-led campaign in Yemen. (Laurent ERRERA from L’Union, France)


About the Author(s)

Oona Hathaway

Gerard C. and Bernice Latrobe Smith Professor of International Law at Yale Law School and Director of the Center for Global Legal Challenges at Yale Law School Follow her on Twitter (@oonahathaway).

Aaron Haviland

J.D. student at Yale Law School, Herbert J. Hansell Student Fellow at the Center for Global Legal Challenges