We can distinguish between three moral approaches to war: pacifism, realism, and just war theory. There are various theoretical approaches to war within the just war tradition. One of the central disputes between these approaches concerns whether war is morally exceptional (as held by exceptionalists) or morally continuous with ordinary life (as held by reductivists). There are also significant debates concerning key substantive issues in the ethics of war, such as reductivist challenges to the thesis that combatants fighting an unjust war are the moral equals of those fighting a just war, and the challenge to reductivism that it undermines the principle of noncombatant immunity. There are also changing attitudes toward wars of humanitarian intervention. One underexplored challenge to the permissibility of such wars lies in the better outcomes of alternative ways of alleviating suffering. The notion of unconventional warfare has also recently come to prominence, not least with respect to the moral status of human shields.