Autonomous weapon systems (AWS) are robotic weapons that can sense and act unilaterally depending upon how they are programmed. Still in their infancy, they select targets and deliver lethality without human supervision. But material developments are required in hardware and software if this self-learning weapon systems are ever to find traction on the battlefield. This timely book unpicks the behavioural and technical challenges to fielding a weapon that can operate independently. The subject's importance is that well-tried concepts which have long made up battlecraft may suddenly no longer be fit for purpose. The book uncovers the highly coupled nature of these machines' routines to demonstrate why it will be enduringly problematic - and unwelcome - to remove human oversight from tomorrow's battlefields.