The concern of whether nonstate actors can undertake an "armed attack" that would trigger a state's right to self-defense has acquired new prominence in the post-September 11 world. This article addresses that concern by examining the Israeli-Hezbollah conflict of July 2006. It argues that since the US invasion of Afghanistan in 2001, states have incurred an increased responsibility for the acts of nonstate actors that operate from their territory. Based on this emerging norm, the argument is that the degree of Lebanon's involvement in Hezbollah's attack against Israel was sufficient to justify the use of force in self-defense by Israel against both Hezbollah and the state of Lebanon. The conclusion is that while this is a potentially dangerous development in international law, there is reason to suggest that it may actually encourage states to prevent their territory from being used by nonstate actors to export violence. KEYWORDS: jus ad bellum, self-defense, nonstate actors, Israeli-Hezbollah conflict.
Under the current regime of jus ad bellum--the law regarding when a state can go to war--self-defense is the most widely accepted basis for a state's resort to using military force. While the threat or use of military force by states is generally prohibited by Article 2(4) of the United Nations Charter, Article 51 of the Charter clearly leaves room for states to use force in self-defense if they are the victim of an "armed attack." This general right of states to individually and collectively resort to armed force in self-defense is therefore not itself contested, yet the Charter's failure to define key concepts such as "armed attack" and a state's "inherent right" to self-defense has necessarily left Article 51 open to interpretation as to the precise scope and limitations of this right. Under pressure from various changes in global realities over the past sixty years, including the advent of nuclear weapons, the proliferation of such weapons, and the increasing threat of global terrorism, the right to self-defense has arguably undergone adaptation, even expansion, through various modes of institutional practice. While much of the debate about the scope of the right of self-defense dates back to the creation of the UN itself, these issues acquired new prominence in the aftermath of the terrorist attacks of September 11, 2001, and the resultant "global war on terror." September 11 and the war against terrorism have thus led to a fundamental reappraisal of at least two crucial aspects of the law of self-defense: the question of "pre-emptive" self-defense and whether or not the right to self-defense applies to attacks by nonstate actors.
In this article, I examine the scope of states' right to use military force in self-defense against nonstate actors, such as terrorist groups, militias, or other "irregular" military forces. After 9/11 and the subsequent US invasion of Afghanistan, this debate focused primarily on whether an "armed attack" can emanate from a nonstate actor for the purposes of Article 51, as well as the degree of state involvement that must be present in such an attack. (1) Several scholars have thus raised the possibility that the 9/11 attacks and the widespread acceptance by the international community of the United States' subsequent invasion of Afghanistan on grounds of self-defense are indicative of a turning point in the development of this norm of international law, such that the threshold has been lowered for attributing attacks by nonstate actors to states. (2) While there is nothing in Article 51 to suggest that armed attacks that justify the use of force in self-defense can only originate from states, the crucial issue for the future development of international law remains the degree to which a state must be involved in such an attack for the purposes of justifying the use of force against, and within the territory of, the state from whose territory the attack originated. …