Phrase used to describe the rivalry between the United States of America and the Union of Soviet Socialist Republics and their sets of allies after World War II. The conflict was marked by the ongoing threat of nuclear warfare. The symbolic starting-point of the war was the speech by Churchill, in 1946, in which he described the “iron curtain” that had descended across Europe. The conflict ended with Gorbachev's rise to power, which resulted in radical change in Soviet international policies.