Cyber war is coming`, announced a landmark RAND report in 1993. In 2005, the U.S. Air Force boasted it would now fly, fight, and win in cyberspace, the `fifth domain` of warfare. This book takes stock, twenty years on: is cyber war really coming? Has war indeed entered the fifth domain? Cyber war will not take place cuts through the hype and takes a fresh look at cyber security. Thomas Rid argues that the focus on war and winning distracts from the real challenge of cyberspace: nonviolent confrontation that may rival or even replace violence in surprising ways. With a mix of technical detail and rigorous political analysis, the book explores some key questions: What are cyber weapons? How have they changed the meaning of violence? How likely and how dangerous is crowdsourced subversive activity?