The Cold War broke out almost immediately after World
War II ended with the defeat of the Axis powers. The Soviet
Union and the United States emerged from the war as the
world's two most powerful countries. But they had very
different ideologies. The United States was a democracy
with a capitalist economic system. The Soviet Union was a
communist dictatorship with an economy entirely
controlled by the government. The rivalry between these
two countries led to conflicts around the world, a buildup
of nuclear missiles, and even the development of the
space program.