In my opinion, the answer is the proletariat. It is a social class of workers who have nothing else in their possession but their labor power. In the aftermath of World War II, two major winners were U.S. and the Soviet Union, and these two superpowers occupied two radically opposed ideologies of capitalism and socialism. Communism, as an ideology, transcends national borders, recognizing only class differences, and therefore the Soviets could claim they defended the rights of the proletariat on a global scale, not just in their own country.