This introduction to the special issue of the same title sets out the context for a critical examination of contemporary developments in sociotechnical systems deployed in the name of security. Our focus is on technologies of tracking, with their claims to enable the identification of those who comprise legitimate targets for the use of violent force. Taking these claims as deeply problematic, we join a growing body of scholarship on the technopolitical logics that underpin an increasingly violent landscape of institutions, infrastructures, and actions, promising protection to some but arguably contributing to our collective insecurity. We examine the asymmetric distributions of sociotechnologies of (in)security; their deadly and injurious effects; and the legal, ethical, and moral questions that haunt their operations.