Just war theory is a long-standing doctrine of military ethics designed to determine the moral legitimacy of armed conflict. It establishes a rigorous set of criteria that must be satisfied for a war to be considered ethically permissible, serving as a guide for policymakers, theologians, and military leaders.
The doctrine is traditionally divided into two primary categories: jus ad bellum, which governs the conditions under which a state may enter a war, and jus in bello, which dictates the moral conduct of combatants during the conflict. In recent discourse, there has been an increasing emphasis on a third category concerning the ethics of post-war settlement and reconstruction, reflecting the evolving nature of global conflict and the pursuit of justice.