The Christian just war tradition has played an important role in political deliberations by many nation-states for seventeen centuries. But does it still have relevance in an age of drones, war by proxy, terrorism, environmental devastation, and failed states? This volume brings together leading scholars from around the world on the viability of the just war tradition in a modern environment, with many essays offering specific historical examples of how the theory plays out in reality. Topics covered include cluster munitions, drones, nuclear proliferation, genocide (and the “responsibility to protect”), environmental concerns, torture, and care for returning soldiers.