The Warsaw Pact or Warsaw Treaty Organization, officially named the Treaty of Friendship, Co-operation and Mutual Assistance, was an organization of Central and Eastern European communist states. It was established on May 1, 1955 in Warsaw, Poland to counter the alleged threat from the NATO alliance. The creation of the Warsaw Pact was prompted by the integration of a "re-militarized" West Germany into NATO on May 9, 1955 via ratification of the Paris Peace Treaties. The Pact lasted throughout the Cold War until certain member nations began withdrawing in 1989, following the collapse of the Eastern Bloc and political changes in the Soviet Union. The treaty was signed in Warsaw on May 14, 1955.