Russia

The Union of Soviet Socialist Republics (USSR) did not collapse in the 20th century in the Fallout world and still existed in the 21st century, prior to Great War. The Soviet Union had foreign and consular service, had diplomatic relations with USA and likely wasn't at war with it in 2077 if a Soviet citizen was able to secure a place in a Vault.

It is not mentioned at all in other parts of the background, especially in background concerning the Great War. The name of the state still confirms that it likely had a communist system of government, but China replaced it as the dominant communist power in the world. It is unknown whether during the Great War the Soviet Union was an ally of China, its enemy, or was neutral towards it, and it is unknown whether it still had its sphere of influence in Europe.