The United States, the Soviet Union, and the End of World War II (2024)

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.

These coordinated military actions came about as the result of intensive and prolonged diplomatic negotiations between the Allied leaders, Roosevelt, Churchill and Stalin, who became known as the “Big Three.” These wartime conferences, which also sought to address issues related to the postwar world, included the November 1943 Tehran Conference. At Tehran, Stalin secured confirmation from Roosevelt and Churchill of the launching of the cross-channel invasion. In turn, Stalin promised his allies that the Soviet Union would eventually enter the war against Japan. In February 1945, the "Big Three" met at Yalta in the Crimea. The Yalta Conference was the most important--and by far the most controversial--of the wartime meetings.

Recognizing the strong position that the Soviet Army held on the ground, Churchill--and an ailing Roosevelt--agreed to a number of things with Stalin. At Yalta, they granted territorial concessions to the Soviet Union, and outlined punitive measures against Germany, including Allied occupation and the principle of reparations. Stalin guaranteed that the Soviet Union would declare war on Japan within 6 months after the end of hostilities in Europe.

While the diplomats and politicians engaged in trying to shape the postwar world, Soviet forces from the east and Allied forces from the west continued to advance on Germany. After a fierce and costly battle, Berlin fell to Soviet forces on May 8, 1945, after Allied and Soviet troops had met on the Elbe River to shake hands and congratulate each other on a hard won impending victory. Although the war in Europe was over, it would take several more months of hard fighting and substantial losses for Allied forces to defeat the Japanese in September 1945, including the first use of the atomic bomb. In accordance with the Yalta agreements, the Soviet Union declared war on Japan in early August 1945, just prior to Japan’s surrender in September.

The alliance between the United States and the Soviet Union during World War II developed out of necessity, and out of a shared realization that each country needed the other to defeat one of the most dangerous and destructive forces of the twentieth century. Ideological differences were subordinated, albeit temporarily, to the common goal of defeating fascism. As a result of this cooperation, the groundwork for a new international system was laid, out of which came the United Nations organization. The Soviets had suffered tremendous human and material losses during the war. Approximately 20 million people were killed, thousands of villages, towns, and cities were destroyed, and the Soviet Union’s economic infrastructure was devastated. Despite the subsequent postwar controversies and the beginning of the Cold War, nothing can diminish the importance of the wartime cooperation between the United States and the Soviet Union.

Office of the Historian

Bureau of Public Affairs

U.S. Department of State