The Scope of an Autonomous Attack

‘Attack’ is an important term of art in international humanitarian law that serves as the basic unit of reference for many targeting obligations. It is often also asserted that human commanders of autonomous weapon systems (AWS) must make legal determinations ‘per individual attack’. Divergent interpretations on what constitutes an attack nevertheless lead to drastically different conclusions with regard to the technology’s lawfulness: interpreted narrowly (‘each shot’), it precludes AWS technology entirely, while interpreted broadly (‘each activation’), it sanctions extensive autonomous activity. This paper theorises that imprecision on the scope of attack is an underappreciated aspect of the AWS controversy that hampers theoretical and diplomatic advancements. The legal boundaries of autonomous attacks are analysed through the lens of targeting law, and a scaling methodology is proposed that allows commanders to determine the maximum extent to which autonomous activity may still lawfully be grouped into one single attack. The paper argues that both overly narrow and broad interpretations are inconsistent with targeting principles and practice, instead favouring a middle-ground approach based on temporal and spatial proximity that properly respects international humanitarian law’s (IHL) balancing philosophy between humanitarian and military interests. Through consideration of practical scenarios, the paper subsequently demonstrates how this impacts the application of targeting rules, such as at what intervals the commander’s duty to verify or cancel is triggered and under what circumstances successive autonomous engagements may be grouped together for proportionality assessments.