In late February 1946, George F. Kennan's "Long Telegram" from Moscow to Washington helped to articulate the US government's increasingly hard line against the Soviets, which would become the basis for United States strategy toward the Soviet Union for the duration of the Cold War. The telegram galvanized a policy debate that would eventually shape the Truman administration's Soviet policy. Washington's opposition to the Soviets accumulated after broken promises by Stalin and Molotov concerning Europe and Iran. Following the WWII Anglo-Soviet invasion of Iran, the country was occupied by the Red Army in the far north and the British in the south. Iran was used by the United States and British to supply the Soviet Union, and the Allies agreed to withdraw from Iran within six months after the cessation of hostilities. However, when this deadline came, the Soviets remained in Iran under the guise of the Azerbaijan People's Government and Kurdish Republic of Mahabad. Shortly thereafter, on 5 March, former British prime minister Winston Churchill delivered his famous "Iron Curtain" speech in Fulton, Missouri. The speech called for an Anglo-American alliance against the Soviets, whom he accused of establishing an "iron curtain" dividing Europe from "Stettin in the Baltic to Trieste in the Adriatic".

A week later, on 13 March, Stalin responded vigorously to the speech, saying that Churchill could be compared to Hitler insofar as he advocated the racial superiority of English-speaking nations so that they could satisfy their hunger for world domination, and that such a declaration was "a call for war on the USSR." The Soviet leader also dismissed the accusation that the USSR was exerting increasing control over the countries lying in its sphere. He argued that there was nothing surprising in "the fact that the Soviet Union, anxious for its future safety, [was] trying to see to it that governments loyal in their attitude to the Soviet Union should exist in these countries".