de facto arrangement had been in existence since 1945, when Soviet forces were maintained in Eastern Europe after the war

headquartered in Brussels, Belgium; members included the U.S., Canada, Portugal, Italy, Norway, Denmark, and Iceland

scope is limited to regions above the Tropic of Cancer

U.S.S.R. in 1954 proposed that it should join to preserve peace in Europe; the proposal was rejected

international collective security alliance; U.S.S.R. dominated armed forces

strategy focus was to prevent recurrence of an invasion of Russian soil as had occurred under Napoleon in 1812 and Hitler in 1941-44

controversial negotiations over how to add to the military command structure when Turkey and Greece joined in 1952

sole joint action was invasion of Czechoslovakia in August 1968

eight member countries pledged the mutual defense of any member who would be attacked