Answer:
After the Russian Revolution, in which the Bolsheviks took over the old Russian Empire in 1918, they faced enormous odds against the German Empire due to World War I, and then again against both domestic and international enemies in the bitter civil war. Tsarist Russia was reorganized as the Soviet Union in 1922. At first, it was treated as an unrecognized Pariah state because of its repudiating the tsarist debts and threats to destroy capitalism at home and around the world. By 1922, Moscow had repudiated the goal of world revolution, and sought diplomatic recognition and friendly trade relations with the world, starting with Britain and Germany. Trade and technical help from Germany and the United States arrived in the late 1920s. Under dictator Joseph Stalin, the country was transformed in the 1930s into an industrial and military power. After the appeasement policy of Britain and France (which Stalin called "pro-fascist"), the Soviet Union shifted from a strategy of antifascist collective security to one of national security. By signing a treaty with Germany in 1939 the Soviet Union hoped to create a buffer zone between them and Germany. In 1941 Nazi Germany invaded the Soviet Union and reached the outskirts of Leningrad and Moscow. However, the Soviet Union proved strong enough to defeat Nazi Germany, with help from its key allies.