After the Second World War the USA (capitalist, democratic bloc) and the USSR (communist bloc) became rival superpowers.
Their rivalry, without a direct war between them, is called the Cold War (about 1945–1991).
It was carried on through an arms and nuclear race, military alliances (NATO 1949, Warsaw Pact 1955, SEATO, CENTO), propaganda, and proxy wars such as the Korean and Vietnam wars.
Newly independent nations like India chose non-alignment. The Cold War ended with the fall of the Berlin Wall (1989) and the break-up of the USSR (1991).