 Unlike prior, shorter-term blocs, the Western and Soviet blocs sought to spread their national ideological differences to other nations.Leaders like U.S. President Harry S. Truman under the Truman Doctrine believed it was necessary to spread democracy whereas the Warsaw Pact under Soviet policy sought to spread communism.After the Cold War, and the dissolution of the ideologically homogeneous Eastern bloc still gave rise to others such as the South-South Cooperation movement.