Responding to Attacks by Non-State Actors: The Attribution Requirement of Self-Defence

Article excerpt


There is controversy about whether and in what circumstances a State may act in self-defence in response to armed attacks carried out by non-State actors. Through an examination of State practice and ICJ decisions, this article examines the requirement that an armed attack must be attributable to the State against which self-defence is exercised. The author argues that there is confusion in the way in which the topic has been dealt with, and seeks to clarify some important conceptual issues. Ultimately, it is argued that the previously accepted 'effective control' attribution threshold permitting self-defence has been altered by the military response in the wake of the 11 September 2001 terrorist attacks, to a test of 'sanctuary and support'.


  If country X, within its borders, is openly tolerating or incapable
  of managing a location where people are consistently attacking a
  neighbour, is it sufficient to say, 'Well, it's within their
  sovereign territory, nobody can do anything about it'? I think that's
  not true and 1 think there's a serious question about whether that's
  what the law ought to be. (1)

The phenomenon of modern terrorism has exposed a serious international legal problem affecting global peace and security. The difficulty can be described as follows. Non-State entities, such as terrorists, carry out attacks on a State ('the victim State'), but operate from or take sanctuary in another State ('the sanctuary State'). The victim State wishes to quell the attackers residing within the sanctuary State's borders. The sanctuary State did not actually carry out or direct the attacks, although it may be idle in preventing or removing the presence of the hostile actors from its soil. Can the victim State lawfully take cross-border action to neutralise the non-State attackers?

In this situation, the elimination of hostile actors or terrorists within the territory of another nation collides with two fundamental principles of international law: territorial sovereignty and the prohibition on the use of force prescribed in article 2(4) of the United Nations Charter ('UN Charter'). The only possible exception to a violation of both of these principles is the right of self-defence set out in article 51 of the UN Charter. (2) Under that provision, all States have a right of self-defence in response to an 'armed attack'. But what level of culpability, if any, is required on the part of the sanctuary State to permit the victim State to exercise its right of self-defence? This question has given rise to an incredible amount of controversy since it emerged as a topic of major global importance when the United States (US) carried out military activities in Afghanistan in the aftermath of the 11 September 2001 ('September 11') terrorist attacks. The issue is fundamentally that of the link required between the sanctuary State and the non-State entity.

In answering this question, this article advances three ultimate propositions. First, that the current position of international law is that an armed attack must be attributable to the State against which self-defence is exercised. Second, the threshold test for that attribution has changed from a State having 'effective control' over the attackers, to providing the attackers with 'sanctuary and support'. Third, this test of attribution is justified as the best principle for protecting international peace and security, and strikes a reasonable balance between self-defence and territorial sovereignty. Additionally, this article attempts to clarify some confusing conceptual problems that have arisen in discussions on this topic.

The article begins by examining the traditional requirements for a valid exercise of self-defence: Sections 1 and 2 discuss the requirements of 'armed attack', as well as 'necessity' and 'proportionality'. Section 3 examines the requirement that an armed attack must be attributable to the State against which self-defence is sought to be exercised. …


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