When can a state engage itself in war?

A state can engage in war when it believes its sovereignty, territorial integrity, or national interests are threatened, or in response to an act of aggression. International law, particularly the United Nations Charter, requires that states seek peaceful resolutions before resorting to armed conflict. Additionally, states may engage in war if authorized by the UN Security Council or to exercise the right of self-defense. Ultimately, the decision to go to war is guided by national policy, legal frameworks, and the specific circumstances at hand.