As a relatively new instrument of warfare, drones are an important tool in the global war against terrorism. Its deployment is often couched in the language of self-defence. However such thesis raises several questions with respect to the concept of self-defence. This article will elaborate on the concept of self-defence, first from a historical perspective and second its current understanding. From therof, the deployment of drones will be assesed from two different approaches; namely the sovereign-right and belligerent-right approach.