The Union of Soviet Socialist Republics (USSR) was a constitutionally socialist state that existed in Eurasia from 1922 to 1991. It was reformed into Russian Federation.
In the original timeline, Skynet launched a nuclear attack on the Soviet Union.The Soviets then launched a nuclear attack in response to the, apparent, American assault.
- Russia is called the "Soviet Union" in early Terminator fiction before 1991 because those fiction was written before the Dissolution of the Soviet Union in the year 1991.
- Terminator 2: Judgment Day was released on July 1st 1991, a full 6 months before the dissolution of the Soviet Union. However it takes place in 1994 and in the end scene witch takes place 30 years after August 29th were Judgment Day never happened so its unknown if the USSR ever dissolved.
- Korolev was built by the Soviet Union.
Union of Soviet Socialist Republics on Wikipedia