Extraterritorial Use of Force against Non-State Actors: PS to Hague Academy Lectures

In July 2021, the author presented a Special Course for the Hague Academy of International Law Summer Courses on the Extraterritorial Use of Force against Non-State Actors. The course focused on two bases for the extraterritorial use of force against non-state actors, namely self-defence and intervention by invitation. The lectures came to a conclusion that may, at first glance, appear contradictory. With respect to the use of force in self-defence, the lectures adopted a restrictive (non-permissive) approach in which the use of force is not permitted save in narrowly construed exceptions. With respect to intervention by invitation, the lectures adopted a more permissive approach in which the use of force is generally permitted and prohibited only in narrowly construed exceptions. This article serves as post-script (PS), to explain the apparent contradiction. It concludes that the main reason for this apparent contradiction is the application of the fundamental principles of international law—sovereignty, territorial integrity and independence—which are consistent with intervention by invitation but are undermined by self-defence against non-state actors.