An NRC-NAE study considered ethical, legal, and societal issues relating to research on, development of, and use of rapidly changing technologies with low barriers of entry that have potential military application (e.g., information technologies, synthetic biology, and nanotechnology) as well as ethical issues associated with robotics and autonomous systems, prosthetics and human enhancement, and cyber weapons. These technologies are characterized by readily available knowledge access, rapid technological advances, the blurring of lines between basic and applied research, and a high uncertainty about their future evolution and applications. This report addresses the ethics of using autonomous weapons that may be available in the future; the propriety of enhancing soldiers’ physical or cognitive capabilities with drugs, implants, or prosthetics; and what limits, if any, should be placed on the nature and extent of economic damage that cyber weapons can cause. The report explores three areas with respect to emerging and rapidly available technologies: the conduct of research; research applications; and unanticipated, unforeseen, or inadvertent ethical, legal, and societal issues. A framework is provided for policymakers, institutions, and researchers to use in thinking about issues associated with these technologies of military relevance.