The original purpose of NATO (North Atlantic Treaty Organization) was to

provide collective security and defense against the threat of Soviet aggression during the Cold War. NATO was established in 1949 as a means of promoting stability, peace, and cooperation among member countries in the North Atlantic region. The organization's primary objective was to deter and defend against potential military aggression by the Soviet Union and its allies, while also serving as a forum for consultation and cooperation on defense and security matters among member states.