Professor Laurie R. Blank, Emory University School, of Law Full examines how international law applies to the use of force in the territory of another state for the purpose of preventing a resurgence of violence after a conflict has ended.
Full tittle: Necessity and Proportionality at the End of Conflict: The Use of Force to Prevent Recurrence of Conflict.
The United States has announced an intended policy of maintaining military forces in Syria after the end of the conflict with ISIS, in order to prevent the resurgence of conflict, prevent Syria from being a platform for jihadists, and prevent Iran from extending a sphere of influence in the area. The backdrop to this decision is the well-accepted determination that the United States decision to pull out of Iraq at the end of 2011 created space for ISIS to emerge as a reconstituted version of al Qaeda in Iraq. The strategic and policy decision to maintain a military presence so as to prevent a rebirth or reconstitution of one of the most brutal terrorist groups of recent decades appears straightforward. A more complicated question, however, is how to assess the lawfulness of the use of force in the territory of another country in order to prevent the re-emergence of violence.
This chapter examines how international law applies to the use of force in the territory of another state for the purpose of preventing a resurgence of violence after a conflict has ended. In the absence of consent or UN Security Council authorization, can self-defense be a justification for a state to use force to prevent the resurgence of conflict? This chapter addresses a series of issues that stem from this broader question, including whether the meaning of armed attack remains constant regardless of whether it is assessed in the absence of conflict or immediately following the end of a conflict, and how necessity and proportionality apply to such uses of force in accordance with the foundational tenets of the international law of self-defense.
The first section addresses introductory issues, including a brief explication of the international law of self-defense, the meaning of the term “use of force” in international law, and the ways in which different types of conflicts end and how to define or identify such endings. The second section analyzes the proper trigger for the right of self-defense, an armed attack or imminent armed attack, and explores whether and how the definition of and threshold for an armed attack might differ in post-conflict scenarios. For example, the nature of the enemy may produce different perspectives on whether and when certain acts constitute an armed attack in this phase between the end of a conflict and a potential re-emergence of violence, as could the location of the acts, the types of acts, or even the manner in which the conflict ended. Finally, the third section queries how necessity and proportionality, the key criteria for the use of force in self-defense, apply or should apply to this proposed scenario. Understanding the scope and parameters of necessity and proportionality demands an inquiry into the legitimate aims of self-defense, as well as a nuanced look at how necessity and proportionality operate and what these two essential criteria are designed to achieve and safeguard.
Keywords: Use of Force, LOAC, Jus Ad Bellum, Law of Armed Conflict, Armed Attack, Necessity, Proportionality, United Nations Charter, Self-Defense, Article 51
In January 2018, then U.S. Secretary of State Rex Tillerson declared that the United States would keep military forces in Syria even after the end of the conflict with ISIS. As Tillerson explained, this continued “military presence in Syria” will be “focused on ensuring ISIS cannot re-emerge.”(1) The backdrop to this decision is the well-accepted determination that the United States decision to pull out of Iraq at the end of 2011 created space for ISIS to emerge as a reconstituted version of al Qaeda in Iraq. The strategic and policy decision to maintain a military presence so as to prevent a rebirth or reconstitution of one of the most brutal terrorist groups of recent decades appears straightforward. A more complicated question, however, is how to assess the lawfulness of the use of force in the territory of another country in order to prevent the re-emergence of violence.
International law provides a detailed and comprehensive framework governing the use of force, set forth in the United Nations Charter. In particular, article 2(4) of the U.N. Charter prohibits the “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.”(2 ) This prohibition is the foundation of the U.N.’s goal of “sav[ing] succeeding generations from the scourge of war, which twice in our lifetime has brought untold sorrow to mankind.”(3) International law provides three exceptions to this prohibition against the use of force in or against another state: the consent of the territorial state, the multinational use of force authorized by the Security Council, or individual or collective self-defense. Under the first exception, which is customary in nature, a state engaged in an internal conflict with a rebel group may seek assistance from other states,(4) or a state may consent to another state using force in counterterrorism operations. The second exception is Charter-based: Article 42 of the U.N. Charter authorizes the Security Council to “take such action by air, sea, or land forces as may be necessary to maintain or restore international peace and security . . . .”(5) For example, the multinational military operation to protect civilians in Libya in the spring and summer of 2011 was in accordance with U.N. Security Council authorization under Article 42.
This chapter focuses on the final exception, self-defense, the most commonly relied-upon justification for the use of force. If the United States maintains a military presence in Syria after the end of the conflict with ISIS, neither of the two above exceptions would apply: there are no suggestions that Syria has consented to the U.S. military currently being in or remaining in Syria and the U.N. Security Council has not authorized and is unlikely to agree to authorize a multinational operation in Syria. Indeed, the United States and its coalition partners have used force against ISIS in Syria since September 2014 in individual and collective self-defense.(6) More broadly, the United States has relied on self-defense as the overarching justification for military action against al Qaeda and other terrorist groups(7) over the past seventeen years, beginning with military operations against al Qaeda and the Taliban in October 20018 and stretching across several countries, including Afghanistan, Pakistan,(9) Yemen,(10) Somalia(11) and, most recently, Syria. However, the stated intention for a continued U.S. military presence is not part and parcel of the existing operations to defeat and end attacks by ISIS or other terrorist groups. Although such operations do pose interesting questions regarding the extent of selfdefense against terrorist groups,12 they do not raise the question of using force — in the form of military forces present in another state’s territory or any other manner — to prevent the reemergence or resurgence of violence.
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Blank, Laurie R., Necessity and Proportionality at the End of Conflict: The Use of Force to Prevent Recurrence of Conflict (February 6, 2019). Necessity and Proportionality in International Peace and Security Law (OUP, 2019). Available at SSRN: https://ssrn.com/abstract=3329720