In 1938 , at the outbreak of World War II , which had a larger population , the Western Allies ( United Kingdom , France , Poland and British Dominions ) or the European Axis ( Germany and Italy )
Canada , the United States , and the European countries among this group formed a military alliance called the North Atlantic Treaty Organization , or NATO , to oppose the Eastern Bloc and their military alliance , the Warsaw Pact , which was composed of the wartime Allies Poland , Czechoslovakia , and the Soviet Union , the ex-Axis powers of Bulgaria , East Germany , Hungary and Romania as well as Albania .