Armies know all about killing. It is what they do, and ours does it more effectively than most. We are painfully coming to realize, however, that we are also especially good at killing our own from the inside out, silently, invisibly. In every major war since Korea, more of our veterans have taken their lives than have lost them in combat. The latest research, rooted in veteran testimony, reveals that the most severe and intractable PTSD–fraught with shame, despair, and suicide–stems from moral injury. But how can there be rampant moral injury in what our military, our government, our churches, and most everyone else call just wars? At the root of our incomprehension lies just war theory–developed, expanded, and updated across the centuries to accommodate the evolution of warfare, its weaponry, its scale, and its victims. Any serious critique of war, as well any true attempt to understand the profound, invisible wounds it inflicts, will be undermined from the outset by the unthinking and all-but-universal acceptance of just war doctrine. Killing from the Inside Out radically questions that theory, examines its legacy, and challenges us to look beyond it, beyond just war.