Wartime relations between the United States and the Soviet Union can be considered one of the highpoints in the longstanding interaction between these two great powers. Although not without tensions--such as differing ideological and strategic goals, and lingering suspicions--the collaborative relationship between the United States and the Soviet Union nonetheless was maintained. Moreover, it was instrumental in defeating Nazi Germany in 1945.
The United States greeted the democratic Russian Revolution of February 1917 with great enthusiasm, which cooled considerably with the advent of the Bolsheviks in October 1917. The United States, along with many other countries, refused to recognize the new regime, arguing that it was not a democratically elected or representative government. The policy of non-recognition ended in November 1933, when the United States, under President Franklin D. Roosevelt, established full diplomatic relations with the Soviet Union, the last major power to do so.
Despite outwardly cordial relations between the two countries, American misgivings regarding Soviet international behavior grew in the late 1930s. The August 1939 Nazi-Soviet Pact, which paved the way for Hitler’s invasion of Poland in September, followed by the Soviet invasion of Poland’s eastern provinces of Western Ukraine and Western Byelorussia, caused alarm in Washington. The Soviet attack on Finland in November 1939, followed by Stalin’s absorption of the Baltic States of Estonia, Latvia, and Lithuania in 1940, further exacerbated relations.
The Nazi invasion of the Soviet Union in June 1941, however, led to changes in American attitudes. The United States began to see the Soviet Union as an embattled country being overrun by fascist forces, and this attitude was further reinforced in the aftermath of the Japanese attack on Pearl Harbor in December 1941. Under the Lend-Lease Act, the United States sent enormous quantities of war materiel to the Soviet Union, which was critical in helping the Soviets withstand the Nazi onslaught. By the end of 1942, the Nazi advance into the Soviet Union had stalled; it was finally reversed at the epic battle of Stalingrad in 1943. Soviet forces then began a massive counteroffensive, which eventually expelled the Nazis from Soviet territory and beyond. This Soviet effort was aided by the cross-channel Allied landings at Normandy in June 1944.