The days of large force-on-force engagements with conventional fielded armies are seemingly gone. Today’s persistent conflict, conducted among civilian populations and fought by small bands of combatants, will be remembered for this alteration in the tapestry of war and for the first large-scale use of unmanned vehicles. According to M. Shane Riza, this “war among the people” and the trend toward robotic warfare has outpaced deliberate thought and debate about the deep moral issues affecting justice and the warrior spirit. The pace of change, Riza explains, is revolutionizing warfare in vitally important ways. A key development is risk inversion, a shifting of risk away from technologically superior combatants and onto all noncombatants. For the first time in history, warriors are not the ones primarily shouldering the dangers and horrors of battle. This inversion and the search for impunity undermine the idea that how we win actually matters as much as winning itself. Though warfare involves human fallibility, there are ethics in striving that give meaning to war on a personal level. In just war theory, this sense of purpose imposes a practical limit on what belligerents can and should do to their opponents. Contemporary robotic warfare, however, may remove combatants’ moral equivalence and it adversely affects the mutual respect upon which to build a lasting peace. Killing without Heart postulates today’s technological wars of combatant impunity may ultimately render unmanned weapons useless with the realization that robotic lethality undermines our strategic objectives. Riza has crafted a timely examination of the moral, ethical, and legal implications of the U.S. military’s future course toward armed unmanned and autonomous robotic warfare. This is a book that will change the way we look at warfare—both for today and well into the future.