Will a State’s self-defence amount to armed attack against a State which has been harbouring / financing terrorist groups, if such terrorist groups attack the victim State either independently or used as a proxy by the hosting state? To what extent may the State then retaliate?

Abstract

The emergence of the phenomenon of global terrorism towards the end of the twentieth century presented a unique challenge for the international community. Terrorist groups – as the events of September 11th, 2001, demonstrated – have proven themselves capable of mounting “armed attacks” which result in significant devastation. In response, states have claimed the right to selfdefence, both against the terrorist groups and the states which harbour/finance them. The United States has led the way, outlining a series of legal doctrines related to the use of force in selfdefence, which include provisions about the necessity of taking preventative action against states deemed “unable or unwilling” to combat terrorism within their borders. These developments pose a significant challenge to longstanding understandings of self-defence in international law. The UN Charter prohibits states from use of force, except in situations of self-defence, though was drafted in the 1940s and had in mind relations between states. It thus struggles to adequately deal with the complexities of the twenty-first century world, in which self-defence is invoked as grounds to take both preventative and retaliatory action against not only terrorist groups, but also the states which are alleged to harbour/finance them. Consequently, the research focuses upon three important questions in relation to the right to self-defence, with a particular emphasis upon the meaning of ‘armed attack’ within Article 51, as applied to the use of force by Non-State Actors. The final chapter undertakes an in-depth examination of the principles of proportionality and necessity, which further constrain the use of force according to Customary International Law. What emerges from this analysis is that powerful states often engage in retaliation of questionable legality against states alleged to harbour/sponsor terrorism. Principles of necessity and proportionality which emerge from customary international law, as well as past ICJ judgements which found force could not be employed against states because of the actions of non-state actors, appear to indicate that it is not strictly lawful to act in self-defence against states which harbour/finance terrorists, especially if the terrorist attack cannot be directly attributed to them, all other options have not been exhausted, and/or there is no UNSC resolution authorising force. This would suggest that retaliation could itself constitute an “armed attack” in violation of the UN Charter. However, there is little that can be done to constrain the behaviour of powerful states, even though it risks severely distorting and politicising the concept of self-defence.