NATO is an intergovernmental military alliance. Members - including most of Western Europe, the United States, Canada and Turkey - agree to mutual defense in response to an attack by any external party.
NATO is based on the North Atlantic Treaty which was signed on 4 April 1949, four years after the end of WW II. It has 28 members, West Germany joined in 1955.The organization was drawn into the breakup of Yugoslavia, and conducted its first military interventions in former Yugoslavia in the 1990s. DW's content tagged "NATO" appears on this page.