This article explores and appraises international legal developments regarding the right to self-defence against vicarious aggression — that is, armed attacks by non-state entities that are sponsored or hosted by a foreign state. Despite efforts to develop a normative framework and mechanisms of accountability to curb states’ use of non-state entities as proxies for armed activity, some states continue to view these entities as valuable tools for the realization of their foreign policy goals. Consequently, international practice shows general recognition of a right of self-defence against non-state armed entities. There is also an emerging body of authoritative opinion, backed by an evolving state practice, that supports the extension of the application of this right against a non-state entity’s host or sponsoring state, provided some conditions are met.
