USSR is short for the Union of Soviet Socialist Republics or Soviet Union. This union was the communist empire run from Moscow. It followed on from the Bolshevik Revolution of 1917 and ended more or less with the fall of the Berlin Wall in 1989. More on this at Communist Infiltration. It did enormous damage and still does. There are deadly effective outposts in universities marketing Cultural Marxism throughout Christendom.
One problem for its advocates is their hatred of Fascists and the Nazis, which are just as much collectivist, just as much tyrannies but not so murderous. Read about the Kulak to know just how bad evil can get. Notice that this is merely what the Wikipedia has to tell us. The reality will have been worse. Of course the Wiki says nothing about the role played by Jews in setting it up.
Some were outside the USSR. They were intended to become part of a world empire. It didn't come to pass in that form.
Soviet Union ex Wiki
The Wikipedia takes a position.
The Union of Soviet Socialist Republics, informally known as the Soviet Union (Russian: Советский Союз, tr. Sovetsky Soyuz) or Soviet Russia, was a constitutionally socialist state that existed on the territory of most of the former Russian Empire in Eurasia between 1922 and 1991.
The Soviet Union had a single-party political system dominated by the Communist Party. Although the USSR was nominally a union of Soviet republics (of which there were 15 after 1956) with the capital in Moscow, it was in actuality a highly centralized state with a planned economy. Much of Soviet society was overseen by national security agencies such as the KGB (which was active from 1954.)
The Soviet Union was founded in December 1922 when the Russian SFSR, which formed during the Russian Revolution of 1917 and emerged victorious in the ensuing Russian Civil War, unified with the Transcaucasian, Ukrainian and Belorussian SSRs. After the death of Vladimir Lenin, the first Soviet leader, power was eventually consolidated by Joseph Stalin,  who led the country through a large-scale industrialization with command economy and political repression. During World War II, in June 1941, the Soviet Union was attacked by Germany, a country it had signed a non-aggression pact with. After four years of warfare, the Soviet Union emerged as one of the world's two superpowers, extending its influence into much of Eastern Europe and beyond.
The Soviet Union and its satellites from the Eastern Bloc were one of two participating factions in the Cold War, a global ideological and political struggle against the United States and its allies; the Soviet bloc ultimately lost, however, having been hit by economic standstill and both domestic and foreign political unrest, an event which marks the beginning of the post-war period. In the late 1980s the last Soviet leader Mikhail Gorbachev tried to reform the state with his policies of perestroika and glasnost, but the Soviet Union collapsed and was formally dissolved in December 1991 after the abortive August coup attempt. Since then the Russian Federation has been exercising its rights and fulfilling its obligations.
That is the Wiki's position. Believe it if you want.