Terrorism, the Use of Force and International Law after 11 September

Abstract

There were at least four possible legal justifications for the use of force against Afghanistan: Chapter VII of the UN Charter, intervention by invitation, humanitarian intervention and self-defence. The United States relied solely on the last justification, with the choice having been based on considerations arising out of the interaction of international politics and international law. In pursuing a claim of self-defence, the US adopted a two-pronged legal strategy: it expanded the focus to include the Taleban; and it worked hard to secure widespread support in advance of military action. As a result, the right of self-defence now includes military responses against States that actively support or willingly harbour terrorist groups who have already attacked the responding State. The US may now be employing similar legal strategies in an effort to develop or extend a right of anticipatory self-defence against terrorist acts.