The Extent and Validity of Yemen’s Consent to the US’s Use of Force

Above: Yemen President Abd-Rabbu Mansour Hadi at UN headquarters on September 21, 2017.  (Photo by Spencer Platt/Getty Images)

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

Although Article 2(4) of the UN Charter prohibits members from threatening or using force against another member, there are certain exceptions that may apply to the U.S. military involvement in Yemen, such as the Yemeni government’s consent. However, recent reports that Yemen’s President Hadi is under house arrest in Saudi Arabia raise deep concerns about the validity of his government’s consent to military operations. In the absence of valid consent, many of the current U.S. operations in Yemen would likely be found to violate the UN Charter’s prohibition on the use of force.

Article 2(4) of the UN Charter and Associated Exceptions

Article 2(4) of the UN Charter states: “All members shall refrain in their international relations from the threat or use of force against the territorial integrity or political independence of any state, or in any other manner inconsistent with the Purposes of the United Nations.” There are three exceptions to this blanket prohibition:

  • A host state may consent to the use of force;
  • A state may use force in self-defense under Article 51 of the Charter; and
  • A state may use force if authorized to do so by the UN Security Council.

The consent exception has some additional qualifiers that are important in the Yemen context.  Consent is limited to “particular conduct by another State . . . to the extent that the conduct remains within the limits of the consent given.” (Draft Articles on State Responsibility, art. 20) Hence an intervening state can only carry out those acts consented to by the recipient of the intervention. In addition, consent given by a representative of a state under duress is invalid.

While we conclude that the primary justification for ongoing military operations in Yemen is consent by the Yemeni government, each form of U.S. military involvement must be analyzed separately to determine whether it triggers Article 2(4) in the first place and, if so, the bounds of any consent given as well as whether the operation can be justified under any of the other exceptions.

Ongoing Airstrikes and Limited Operations

The only ongoing direct use of force by the United States in Yemen is against the Islamic State, al-Qaeda, and associated groups, including al-Qaeda in the Arabian Peninsula.  There is little doubt that the repeated use of military weaponry to cause significant property damage and loss of life within the territory of another sovereign state qualifies as a “use of force” under Article 2(4).  The question, then, is whether any of the exceptions to the prohibition on the use of force applies.

Because there has been no Security Council authorization regarding Yemen, there are two possible legal bases for these uses of direct force: consent or self-defense.  Prior to February 7, 2017, the U.S. counterterrorism operations took place with the consent of the Yemeni government.  On February 7, 2017, however, Yemen withdrew its consent for U.S. anti-terror ground missions after children were caught in the crossfire of a firefight between the Navy’s Seal Team 6 and suspected terrorists. It does not appear that the government withdrew consent for air operations. At present, there is no public information suggesting the government has further restricted consent or reversed its withdrawal of consent for ground operations. Assuming the Yemeni government continues to consent to air operations but not ground operations, then air operations qualify for the consent exception.  Any ground operations that have taken place after February 7, 2017, however, must be based exclusively on a self-defense justification.

In September 2014, the United States filed an Article 51 letter, as required for any use of force in self-defense under Article 51, to justify its use of force in Syria. In that letter, Ambassador Samantha Power explained that the United States was acting against the Islamic State in Syria in its self-defense and the collective self-defense of allied states, including Iraq, which had expressly requested its assistance.  No similar letter has been filed regarding U.S. military operations against the Islamic State and al-Qaeda and its affiliates in Yemen.  This suggests that the United States is not operating in Yemen under Article 51 and in self-defense. If that is correct, however, then the United States would need to limit its military operations to those to which the Yemeni government has consented – air operations only.  To the extent it is exceeding that consent, its use of force may violate the UN Charter’s prohibition on the use of force.

Houthis Attacks on U.S. Navy Ships and Response

The one direct use of force by the United States against the Houthis took place after the Houthis fired on U.S. Navy ships in 2016.  As discussed in the first Article in this series, that use of force was justified as an act of self-defense (and the Obama Administration filed an Article 51 letter to that effect).  At present, the Houthis do not appear to pose any continuing threat to the United States and therefore self-defense would not be available to the United States as a justification for any renewed use of force against the Houthis in Yemen.

U.S. Military Assistance to the Saudi-Led Coalition

Although the United States is not presently using direct force against the Houthis in Yemen, it is providing military weapons, training, and other assistance to the Saudi-led coalition in Yemen.  Such support can cross the use of force threshold and thus bring a state into violation of Article 2(4) unless it is justified under one of the permitted exceptions to the prohibition on the use of force.

In the Military and Paramilitary Activities in and Against Nicaragua case, the International Court of Justice held that military assistance provided by the United States to a rebel group was an illegal “use of force” against Nicaragua. Unlike in Nicaragua, however, here the United States is not providing military assistance to a rebel group attempting to overthrow a government.  Rather, it is providing assistance to a multinational coalition that is intervening at the request of the recognized government of Yemen. Whether the provision of support implicates Article 2(4) thus turns (again) on the scope of Yemen’s consent.

Here, President Hadi’s request to the Saudi-led coalition asked that it use “all necessary means” to combat the Houthi-Saleh alliance, a request that arguably includes the use of U.S. military assistance. Notably, President Hadi’s letter requesting assistance was directed towards specific countries (Saudi Arabia, United Arab Emirates, Bahrain, Oman, Kuwait, and Qatar), not the international community in general.  Any use of force by a state other than those to whom the letter was addressed may therefore be a violation of Article 2(4). Consent, after all, is not transitive—a state that has received consent may not transfer that consent to another state without the permission of the host state. In the context of the Saudi-led coalition’s operations against the Houthis in Yemen, however, the United States is not acting directly—it is acting exclusively through the Saudi-led coalition. Even its refueling missions take place outside of Yemeni airspace.  Yemen’s request to the Saudi-led coalition for assistance using “all necessary means” can be reasonably understood as authorization of this form of assistance, as long as U.S. actions are channeled through the states to which Yemen granted consent. This conclusion is bolstered by statements by Yemeni government officials indicating support for the U.S. role. For example, in August 2017, Yemen’s ambassador to the United States said, “We need the U.S. government to continue to lend its political and logistical support to the legitimate government and the Arab coalition.” In addition, on October 13, 2017, the Yemeni Embassy to the United States issued a statement praising the U.S. strategy opposing Iran, which “exposes Iran’s attempts to use the Houthi rebels as puppets to destabilize the region.”

At the moment, U.S. military assistance to the Saudi-led coalition appears to fall within the scope of the Yemeni government’s consent to the actions of the Saudi-led coalitions operations. If, however, the Yemeni government were to withdraw its consent to the Saudi-led coalition’s operations or if the Yemeni government were to make clear that it did not consider U.S. support for the coalition efforts to fall within the scope of its consent, then that support would have to cease to prevent a violation of Article 2(4).

House Arrest of President Hadi and the Validity of His Consent

As the foregoing analysis shows, the central legal basis for U.S. operations in Yemen is the consent of the Yemeni government.  However, news reports suggest that Saudi Arabia has placed Yemen’s President Hadi “under de facto house arrest in Riyadh because they deemed his political activities in the liberated port city of Aden as too meddlesome.” Reports further suggest that Saudi Arabia has prevented him, his sons, ministers, and military officials, from returning home.  Salah al-Sayadi’s, a former Yemeni minister of state, resigned from office on March 21, 2018, just days after stating that Hadi was under house arrest and calling for his release. These developments raise dire concerns about the validity of any consent given by President Hadi on behalf of Yemen because consent given by a representative of a state under duress is invalid (Vienna Convention on the Law of Treaties, art. 51). The continued house arrest of President Hadi could, therefore, imperil the legal validity of the U.S.’s counterterrorism operations, the Saudi-led coalition’s operations against the Houthis, and the U.S. support for those operations.

 

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