List of military alliances

A military alliance is a formal agreement between two or more parties concerning national security in which the contracting parties agree to mutually protect and support one another militarily in case of a crisis that has not been identified in advance.

Military alliances differ from coalitions, which are formed for a crisis that already exists.

Numerous forms of military and defensive alliances have existed between states since early human history.

This is a comprehensive list of the most important alliances.

(ABCANZ Armies) United States