Throughout history society has determined specific rules of engagement between adversaries in armed conflict. With advances in technology, from armor to in the Middle Ages to nerve gas in World War I to weapons of mass destruction in our own time, the rules have constantly evolved. Today, when killing the enemy can seem palpably risk-free and tantamount to playing a violent video game, what constitutes warfare? What is the effect of remote combat on individual soldiers? And what are the unforeseen repercussions that could affect us all? Lt Col Wayne Phelps, former commander of a Remotely Piloted Aircraft unit, and Lt Col Dave Grossman, author of the landmark work On Killing and a leading scholar of the effects of killing on the human psyche, address these questions and many others as they tell the story of the men and women of today's "chair force." Exploring the ethics of remote military engagement, the misconceptions about PTSD among RPA operators, and the specter of military weaponry controlled by robots, their book is an urgent and compelling reminder that it should always be difficult to kill another human being lest we risk losing what makes us human.