The North Atlantic Treaty was signed in Washington on 4 April 1949, creating an alliance of 12 independent nations committed to each other's defense. Four more European nations later acceded to the Treaty between 1952 and 1982. See also several items on NATO enlargement to the East, impact on the PFP members and others: NATO Enlargement: The Process and Allied Views, Congressional Research Service Document, by Paul E. Gallis (Washington, DC, July 1, 1997) NATO Enlargement: U.S. and International Efforts to Assist Potential New Members, General Accounting Office Report to the Chairman, Committee on International Relations, House of Representatives (Washington, DC, June 27, 1997) Non-Article V NATO military deployments which do not fall under the Article V mutual defense clause for example, the IFOR deployment in Bosnia. NSC National Security Council. NATO Supply Center. ODIHR
During the postwar period until the dissolution of the Soviet Union in 1991, the primary collective defense agreement of the Western powers against the military presence of the Warsaw Pact nations in Europe. Founded in 1949. Its military and administrative structure remained intact after 1991, but early in 1994 the Partnership for Peace offered partial membership to all former Warsaw Pact nations and former republics of the Soviet Union.