The essays in this volume illustrate the difficult real world ethical questions and issues arising from accelerating technological change in the military and security domains, and place those challenges in the context of rapidly shifting geopolitical and strategic frameworks. Specific technologies such as autonomous robotic systems, unmanned aerial vehicles, cybersecurity and cyberconflict, and biotechnology are highlighted, but the essays are chosen so that the broader implications of fundamental systemic change are identified and addressed. Additionally, an important consideration with many of these technologies is that even if they are initially designed and intended for military or security applications, they inevitably spread to civil society, where their application may raise very different ethical questions around such core values as privacy, security from criminal behaviour, and state police power. Accordingly, this volume is of interest to students of military or security domains, as well as to those interested in technology and society, and the philosophy of technology.