The international alliance formed during the Cold War by Western nations was NATO, the North Atlantic Treaty Organization. Established in 1949, NATO was created as a collective defense agreement among member states, primarily to counter the threat posed by the Soviet Union and its allies. The alliance included the United States, Canada, and several Western European countries. NATO's foundation was predicated on the idea that an attack against one member would be considered an attack against all, thereby promoting mutual security. Over the years, NATO evolved, addressing new security challenges and expanding its membership, playing a crucial role in international relations.