The Western democracies and the Soviet Union discussed the progress of World War II and the nature of the postwar settlement at conferences in Tehran (1943), Yalta (February 1945), and Potsdam (July-August 1945). After the war, disputes between the Soviet Union and the Western democracies, particularly over the Soviet takeover of East European states, led Winston Churchill to warn in 1946 that an "iron curtain" was descending through the middle of Europe. For his part, Joseph Stalin deepened the estrangement between the United States and the Soviet Union when he asserted in 1946 that World War II was an unavoidable and inevitable consequence of "capitalist imperialism" and implied that such a war might reoccur.
The Cold War was a period of East-West competition, tension, and conflict short of full-scale war, characterized by mutual perceptions of hostile intention between military-political alliances or blocs. There were real wars, sometimes called "proxy wars" because they were fought by Soviet allies rather than the USSR itself -- along with competition for influence in the Third World, and a major superpower arms race.
After Stalin's death, East-West relations went through phases of alternating relaxation and confrontation, including a cooperative phase during the 1960s and another, termed d‚tente, during the 1970s. A final phase during the late 1980s and early 1990s was hailed by President Mikhail Gorbachev, and especially by the president of the new post-Communist Russian republic, Boris Yeltsin, as well as by President George Bush, as beginning a partnership between the two states that could address many global problems.
Telegram to Truman translation