Another hole in the Wall? Evaluating the legality of Egypt's 2017 airstrikes against non-state actors in Libya under the jus ad bellum

In May 2017, the Egyptian armed forces conducted airstrikes against non-State targets in the neighbouring State of Libya in response to a series of attacks perpetrated against groups of Coptic Christians on Egyptian territory, killings later claimed by the self-styled Islamic State. In justifying its use of armed force, resort to which is generally impermissible in international law, Egypt purports to rely upon two exceptions to this general rule, namely: (i) authorisation on the part of the United Nations Security Council; and (ii) self-defence, while also invoking the doctrine of military assistance on request (or intervention by invitation). This article tests the legality of Egypt’s airstrikes—which have yet to be subjected to scholarly attention—in light of the three foregoing justifications. In so doing, the article evaluates the implications of this use of force for the jus ad bellum, particularly the law regulating resort to force by way of response to an armed attack for which not another State, but a non-State actor, is responsible.