Self-defence against non-state actors: Making sense of the ‘armed attack’ requirement

Whether States can act in self-defence against armed attacks carried out by non-State actors is one of the major debates of contemporary international law. It has relevance: the issues are significant and implicate a ‘cornerstone rule’ of the discipline, the prohibition against the use of force.¹ It has drama: ‘two main camps’² are said to face each other in what is now frequently (if simplistically) portrayed as an epic argument opposing ‘restrictivists’ and ‘expansionists’.³ It has focus: positions are clearly articulated; academics take sides - where do you stand on the ‘unwilling or unable’ test;⁴ what’s your view on the ‘Bethlehem Principles’;⁵ have you signed the ‘Plea against the Abusive Invocation of Self-Defence’?⁶ - and do not mince words.⁷.