A period of increasing tension between the former Allies: the United States of America and Britain, and the Soviet Union. This tension resulted out of key differences in ideology between the two sides, America and Britain were democratic, capitalist societies, where governments were elected and The Soviet Union was a communist dictatorship with one party rule. After the war, these differences, alongside the race to develop nuclear weapons, caused escalating tension. Although no direct conflict broke out, the tension continued until the fall of communism in 1991.