State Responsibility for U.S. Support of the Saudi-led Coalition in Yemen

This article is the latest article in our forum on the Yemen crisis and the law.

The international law of state responsibility, captured in the International Law Commission’s (ILC) Draft Articles on State Responsibility, provides a possible ground on which the United States may be liable for its assistance to the Saudi-led coalition.  Liability likely would turn on the bounds of U.S. intent and whether the United States knew that its aid would actually facilitate an internationally wrongful act.  For a broader analysis of the legal framework for state responsibility for assistance to foreign forces, see Ryan Goodman and Miles Jackson’s post.

U.S. Responsibility for the Saudi-Led Bombing Campaign

ILC Article 16, which is understood to reflect customary international law, provides that: “A State which aids or assists another State in the commission of an internationally wrongful act by the latter is internationally responsible for doing so if: (a) that State does so with knowledge of the circumstances of the internationally wrongful act; and (b) the act would be internationally wrongful if committed by that State.”  There is a strong case that U.S. support for the Saudi-led coalition meets this test.

Sub-section (b) is clearly met by U.S. support for the coalition.  Any bombings that indiscriminately violate international humanitarian law would be illegal if they were conducted by the United States itself, rather than by the Saudi-led coalition.  It is true that the United States is not a party to Protocol II of the 1949 Geneva Conventions governing non-international armed conflicts.  However, as a matter of treaty and customary international law, the United States is legally obligated to follow the full range of international humanitarian law obligations that apply to parties to a non-international armed conflict.  Notably, these obligations are much broader than those that are subject to prosecution under the U.S. War Crimes Act.

Sub-section (a) presents more difficulty and requires careful analysis of the assisting state’s (here the U.S.’s) requisite intent.  The ILC Commentary on the Draft Articles, which is meant to provide clarity, unfortunately does not entirely succeed on this point.  In its commentary to Article 16(a), the ILC stipulates two related requirements:

  • first, “the relevant State organ or agency providing aid or assistance must be aware of the circumstances making the conduct of the assisted State internationally wrongful;” and
  • second, “the aid or assistance must be given with a view to facilitating the commission of the act, and must actually do so.”

At first glance, these two requirements may appear inconsistent.  They can be reconciled, however, if the first element is understood to require knowledge that the aid or assistance facilitated an internationally wrongful act—that is, knowledge of the wrongfulness of the action to be taken by the assisted state.  The second condition then would be understood to require intent to facilitate the action taken by the state, even if the state did not specifically intend that act’s wrongfulness.  Understood in this way, the ILC Commentary corresponds relatively closely to the text of Article 16 itself.

Applying this reading to the Saudi-led campaign, the second condition outlined above is clearly met: the United States has provided support to the Saudi-led coalition—including munitions, intelligence, and mid-air refueling—with a view to facilitating the coalition’s military campaign.  As described in earlier Articles in this series, this support has, in fact, facilitated that bombing campaign.  This type of aid need not have been essential to the wrongful act to fall within Article 16; according to the ILC Commentary, “it is sufficient if it contributed significantly to that act.”  Such significance may turn on the relationship between the assistance rendered and the internationally wrongful act.  In a previous post, Harriet Moynihan of Chatham House explained that this “nexus element” has two dimensions: scale and remoteness.  ILC member Nikolai Ushakov noted during the Commission’s 1978 session: “[P]articipation must be active and direct. It must not be too direct, however, for the participant then becomes a co-author of the offence, and that [goes] beyond complicity. If, on the other hand, participation [is] too indirect, there might be no real complicity.”  While the ILC Commentary also contemplates the inclusion of contributions that are less than “significant,” this Article agrees with Ryan Goodman and Miles Jackson that a more lenient threshold has not yet reached the status of customary international law.  Regardless of the metric, arming and mid-air refueling undoubtedly qualify as a significant contribution to the bombing campaign.

The harder question is whether the United States’ assistance meets the first requirement—that the United States knew that the aid or assistance it provided facilitated an internationally wrongful act.  As the ILC Commentary puts it, “[i]f the assisting or aiding State is unaware of the circumstances in which its aid or assistance is intended to be used by the other State, it bears no international responsibility.”

As noted above, there is some ambiguity in the Commentary as to whether the assisting state must intend to facilitate the wrongful act—that is, that it not only intends the act to occur but intends for it to occur in an internationally wrongful manner.  A number of commentators have concluded that “knowledge” is the correct measure.  But there is disagreement about what knowledge requires.  Harriet Moynihan states that knowledge “means actual or near certain knowledge of specific illegality on the part of the recipient state.”  Intent in this view is satisfied by “knowledge or virtual certainty that the recipient state will use the assistance unlawfully.”  Ryan Goodman and Mile Jackson, however, adopt a less stringent test in which mere knowledge of the circumstances is sufficient: “The assisting State has intention to facilitate and/or knowledge of the circumstances of the internationally wrongful act.”

The United States is undoubtedly aware that there have been numerous credible allegations of violations of international humanitarian law (IHL).  Therefore, its support for the Saudi-led coalition almost certainly meets the less stringent knowledge test; it may also satisfy the more stringent “actual or near certain knowledge of specific illegality,” though that is a higher bar to clear.

U.S. Responsibility for Facilitating Torture

As discussed previously, the United Arab Emirates—a member of the Saudi-led coalition—has been accused of torturing AQAP suspects in their terrorism detention facilities in Yemen.  The Associated Press reported that U.S. officials have directly participated in interrogations at said facilities.  If substantiated, acts of torture, as well as cruel and inhumane treatment, would constitute an “internationally wrongful” act pursuant to sub-section (b), as a matter of both treaty and customary international law.

Again, the primary challenge comes from sub-section (a)—knowledge of facilitating the internationally wrongful act. At the moment, there is insufficient public information about the degree of involvement in the alleged torture or the knowledge of U.S. forces about the torture to arrive at a judgment on this issue.  But there is enough public information to suggest that the test could potentially be met and therefore an investigation would be warranted.

Mitigating Measures

The United States could implement mitigating measures to lessen its risk of liability under Article 16—and it has reportedly sought to do so at least with regard to the bombing campaign.  When the U.S. restarted its assistance in June 2017, it sought and received assurances that Saudi Arabia would take greater precautions to adhere to IHL. (Indeed, the prior cessation of support and subsequent decision to seek assurances reveals that the United States was very much aware of credible allegations of IHL violations by the coalition to that point.)

Credible assurances may mitigate liability because they may provide reason to believe that the United States does not have “actual or near certain knowledge” that IHL violations will occur.  Yet if those assurances are not credible, then they cannot insulate the United States from liability.  Some have argued that Saudi Arabia’s military is incapable of adhering to IHL due to serious, systemic problems and, as a result, any assurances could not mitigate U.S. responsibility.  Furthermore, since the restart of U.S. assistance, several airstrikes have taken place resulting in the deaths of civilians. Indeed, this week there was yet another reported strike on civilians in Yemen—this time an attack on a wedding that reportedly killed more than twenty people and wounded dozens of others.   A continuing pattern of IHL violations after the issuance of assurances makes it more likely that the United States has “actual or near certain knowledge” that there will be future IHL violations by the Saudi-led coalition despite assurances to the contrary—and thus that the Untied States is responsible for aiding an assisting an internationally wrongful act under Article 16.

Image: Ibrahem Qasim via Wikimedia Commons. 

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).

Alexandra Francis

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

Alyssa Yamamoto

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

Srinath Reddy Kethireddy

J.D. student at Yale Law School, Student Director of the Center for Global Legal Challenges

Aaron Haviland

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