In 2002, the Bush administration published a new National Security Strategy, which argued that, in the twenty-first century, it was necessary for the United States not merely to defend itself but to use military force to prevent threats such as terrorist attacks and weapons of mass destruction. Is preventive force just? Is it effective? And what can the biggest example of this doctrine in action, the war in Iraq, tell us about the future of preventive force? Peter Robinson speaks with Victor Davis Hanson, Anne-Marie Slaughter, and Stephen Stedman.