Fragmented Wars

The use of force against armed groups located in other States is not new, but began receiving heightened attention as a result of U.S. operations in Afghanistan following the attacks of September 11, 2001. The high-profile nature of these events, the resoluteness with which the United States asserted its right to self-defense against an armed group, and the international support that it received all led to increased attention to the surrounding legal matters. Much of the debate centered upon the basic question of whether a State has a right to self-defense in response to attacks perpetrated by a non-State actor located in the territory of another State, absent attribution of the attack to the other State. Other important issues included the classification of hostilities between the State and such a group, and rules governing the conduct of the parties. This chapter sets out to draw together the threads of these debates from the last fifteen years, to analyze new questions that have emerged, examine how they impact upon each other, and suggest a way forward for overcoming legal challenges.