This contribution investigates restrictivist reasoning on the origin of armed attacks, and concentrates on the interpretation of Article 51 of the UN Charter and the use of state practice. One particular aspect is examined: the linkage of the armed activities of non-state actors to a state required for an exercise of the right of self-defence to be justified in relation to that state. Many authors have moved away from a restrictive interpretation of Article 51 of the Charter and customary international law, and have proposed various legal constructs –complicity, aiding and abetting, harbour and support, unwillingness or inability to act– to allow for the invocation of self-defence even when armed activities of non-state actors cannot be attributed to a state and its substantial involvement is doubtful. Noticeable among authors generally, with certain exceptions, is a certain lack of concern to account for whatever method of interpretation or analysis they employ.