The Soviet Union consisted of 15 Soviet republics: Armenia, Azerbaijan, Belarus, Estonia, Georgia, Kazakhstan, Kyrgyzstan, Latvia, Lithuania, Moldova, Russia, Tajikistan, Turkmenistan, Ukraine, and Uzbekistan. The country fought on the side of the Allies in World War II. The Soviets also offered assistance to Mao Zedong's communist regime in China until the mid-1950s, when ideological disputes lead to a breakdown of relations between the two powers.
The Sino-Soviet split was caused primarily by a debate over ideological orthodoxy and the nations’ differing interpretations of Marxist–Leninist doctrine, both which had shifted to support their own national interests. Led by Premier Nikita Khrushchev, the Soviet Union had begun adopting policies which favored a more peaceful coexistence and open relations with the west, while the Chinese regime remained staunchly Stalinist, a school of thought promoting national and ideological protectionism and intense mistrust of any non-communist government. Chinese leadership saw the softening of Soviet communism and relative warming of Soviet–western relations as nothing short of blasphemy against their Marxist ideals and came to view the Soviets with almost as much distrust as the nations of the west. The tension may have been exacerbated by disputes over territories such as the Soviet puppet state of Mongolia as well as Soviet land along the Amur and Argun rivers, all of which the Chinese claimed as rightfully theirs.
This divide in the communist world was viewed primarily with jubilation among capitalist powers, who saw their two main opponents become one another’s enemies almost overnight. As part of the response to this split, the nations of the west largely welcomed the change in relations with the USSR, adopting a less aggressive stance toward the Soviets’ new, somewhat softer form of communism (this is a point of divergence from our own universe, in which all three parties simply remained mutually hostile). The radical Chinese were pushed further away from both eastern and western spheres, eventually allowing them to take the stage as the prime advocate of communism worldwide and become the main antagonist of the cold war.
Due to divergence in the Fallout universe, the USSR did not dissolve in 1991 and continued to exist well into the 21st century, theoretically up until the Great War. While the exact reasons for the USSR’s survival are unconfirmed, certain factors can be presumed to have played a large role; the relative warming of relations between east and west would have allowed the US–Soviet arms race to subside at least partially, putting less of a strain on the Soviet economy. This would have lessened, at least to some extent, the intense poverty which was so prevalent in the USSR and in our timeline led to widespread dissolution with the Communist Party’s system of economic governance. Additionally, the Fallout universe’s hallmark absence of information technology would have lessened the influence of western media and culture which in our timeline was so ubiquitous in the later years of the USSR and ultimately led to its downfall through lack of popular support for the ruling party. The difference in history between universes leaves many of the USSR’s affairs between World War II and the Resource Wars (a period of almost 100 years) a mystery, or at least unconfirmed within Fallout canon.
The Soviet Union is known to have had a consular service and foreign service and even maintained strong consular relations with the United States. There was a Soviet consulate in Los Angeles (which Natalia's grandfather worked at), suggesting that Soviet–American relations were good enough in 2077 that American and Soviet citizens were able to visit each other's countries. However, there is evidence that the USSR was still considered at odds with the west, and was at the very least suspected of espionage by a part of the American populace.
During the Resource Wars, the Soviet Union was in no direct conflict with the United States, with no real evidence suggesting it played much of a role in the international situation at all. The USSR had access to sufficient reserves of petroleum and uranium (particularly within the Caucasus region and the central steppes, as well as in the satellite state of Romania), and likely pursued policies of isolationism and economic protectionism, consolidating its energy sources and weathering the storm of shortages on its own, consigned not to invade other nations so long as it was not invaded itself.
It is unknown what role the USSR played in the Great War, as it considered both sides of the war far from its allies. The Soviets and Chinese remained hostile throughout the 2000s, and there was always deep distrust between the US and USSR, as had been the status quo between communist and capitalist nations for over a century. The possibility of a war between the eastern and western powers was still present in the minds of the people, and considered by some to be a real threat.  There is no evidence suggesting Soviet support for either side of the Sino-American War, although they were doubtlessly drawn into the subsequent thermonuclear exchange, as it involved every major world power. Given the international situation, it is likely that in the final hours of modern civilization, the Soviets found themselves pitted not only against China or the western powers, but in a mutual destruction scenario with both factions at once.
The reason for China’s status as the primary communist power and enemy of the west in the Fallout universe is not canonically stated, but a connection can be assumed to the Sino-Soviet Split and subsequent improvement of Soviet–Western relations – the latter of which is necessary to explain the survival of the USSR and Warsaw Pact and therefore maintain the Cold War culture and feel central to the Fallout world.
- Ukraine (mentioned in Fallout: New Vegas)
- When R. Scott Campbell was asked why China was the U.S. enemy and not the Soviet Union, he answered that it was because he heard the Russian mob firing their guns in the street while he was telephoning a Muscovite. After that, he had a difficult time believing that the U.S.S.R. would be in a position to threaten the world any time soon.
- Historical sources show that prior to its breakup in our timeline in 1991, the economy of the USSR was strained to the breaking point by its constant arms race with the US. When the Soviet government ended its participation in the arms race to prevent economic collapse, this disillusioned the populace to the longstanding propaganda campaign of fear and aggression towards the west, essentially admitting that the communist government was unable to stand up to the western powers. This was a huge factor leading to the declarations of independence by all of the Soviet republics and the dissolution of the Soviet Union.
- The Fallout universe was devised around the ideas of retro-futurism and a ’50s-era feel as well as the legacy of a global thermonuclear war. The creators of Fallout decided the best and simplest way to explain this was to have the Cold War of our timeline continue well into the 21st century, maintaining the culture of the Red Scare and its east–west mentality. In order for these to make any sense at all, the Soviet Union would have to still exist as a communist country in the universe's lore leading up to the war – but in order to survive that long in the first place, the USSR could not remain the main communist adversary of the United States. Therefore, the partial thaw of east–west relations and subsequent rise of China as the primary communist world power were necessary events in the Fallout lore in order to explain the continued capitalist–communist cold war it relies on for its central plot.
- The Soviet Union is mentioned in the biography of Natalia, one of the pre-made characters in Fallout, whose grandfather was a Soviet diplomat at the USSR’s consulate in Los Angeles.
- The AK-112 assault rifle was the standard service rifle used by the prewar Soviet Military.
- The Molotov cocktail is named after the Soviet foreign minister Vyacheslav Molotov (the weapons themselves were actually first used by Finnish soldiers in the Soviet–Finnish Winter War, but became known by the Soviet minister’s name instead).
- According to J.E. Sawyer, Gorobets in Fallout: New Vegas is the descendant of Ukrainian immigrants to the US.
- In Fallout 3, the Museum of Technology states that the Soviet Union, along with China, "constantly refuted" the American claim that they put the first man in space in 1961.
- Music by Ukrainian Jack Shaindlin is played on Galaxy News Radio in Fallout 3.
- Vladimir Lenin, the founder of the Soviet Union who attempted to transition Russia into Communism, is mentioned briefly by the character No-bark Noonan in Fallout: New Vegas.
|The following is based on Fallout Tactics and some details might contradict canon.|
- The AK47 and RPG-7, common weapons in Fallout Tactics, were designed and manufactured by the Soviet military.
- The wreckage of the Soviet space station Mir appears as an Easter egg in a special encounter.
|End of information based on Fallout Tactics.|
|The following is based on Fallout Extreme and has not been confirmed by canon sources.|
- In the canceled Fallout Extreme, it was planned that the main characters would pass through Russia on their way to China.
|End of information based on Fallout Extreme.|
- In The Armageddon Rag, Vol. 4, Crazy Ivan is from the USSR.
- In Fallout 4 the cover of an issue of Astoundingly Awesome Tales depicts a "Mad Russian" riding on a bear. Bears were commonly used as a symbol to represent Russia and the USSR as a whole.
- In Fallout 4, The Switchboard's research terminal, under saved transcripts dated June, 19, 2067 the Soviet Union is mentioned in a 'USSR China Attack' Scenario.
- In Fallout 4, Codsworth will talk about the "Red Menace" in a certain conversation path, when asked what he is talking about he will mention "The Russians and Chinese", implying that American society harbored intense distrust of the USSR as well as China as both were communist nations during the Cold War.
- In Fallout 4, bottles of vodka are marked as being imported from Russia.
- In Fallout 4, it is revealed in one of Eddie Winter's holotapes that he knew of a Russian hitman named Aleksandr Strelnikov.
- ↑ A diplomat from the Soviet Consulate in Los Angeles was able to secure a place in Vault 13 and Natalia, one of the Fallout 1 pre-made characters, was the diplomat's grandchild
- ↑ In the Helios One terminal entry "Can I Tell Him?" urging complete secrecy, A hypothetical situation is presented that results in the USSR acquiring national secrets, with "Ivan Bullykov will get more than lunch money out of your kids. He'll have national secrets! And while they're parading him through Red Square as a national hero, your children will be working in forced labor camps, right next to you and your beautiful young wife".
- ↑ Wastewater treatment plant terminal entries: Devlin - "Answer me this, Specialist Buttinski: if the American people are overrun by Kremlin Joe and his Chicom cronies, what good will clean drinking water be?"
- ↑ The nuclear Armageddon in the back-story was between the US and China. After shipping several people asked me why China and not the old standby, the Soviet Union. I made the choice when I remembered experiences with Oleg, a Moscow developer I worked with months before when I was assistant-producing a typing game. Once, in the middle of a phone conversation, I heard some muffled bangs, and the phone went quiet. When I asked him what the noise was, he replied, “Oh, it was just the Russian mob firing their guns in the street.” I thought he was joking – he wasn’t. After that, I had a really hard time believing that the once mighty USSR would be in a position to threaten the world any time soon. So I turned to the next major communist country that typifies “the East”: China. 
- ↑ In line with Marxism, communism has never been implemented because for communism to exist the state must be dissolved and be proceeded by a worldwide socialist phase, the U.S.S.R. was in fact a state socialist system, a so called "dictatorship of proletariat".