In Chapter 4, I investigate the emergence and evolution of the USA’s targeted killing programme, focusing mainly on its origins within the CIA and its transformation from a limited, ad hoc method to a systematic and institutionalised form of militarised counterterrorism. I question whether it represents the erosion of international and domestic prohibitions on assassination and find that it does not; those prohibitions continue to exist and play a normative role in shaping how force is used, but they have changed in content – they refer to something different than before. Central to this process were legal arguments and bureaucratic politics designed to adjust the delegation of authorities across the agencies of the US security apparatus, facilitated by the development of armed unmanned aerial vehicles, which supplied an essential means, and by pressure from the Bush and Obama administrations.