Concept:
The Union of Soviet Socialist Republics (USSR) was a federal socialist state that existed from 1922 to 1991.
• Breakup: In December 1991, the USSR dissolved into 15 independent sovereign states.
• The Republics: These included the Baltic states, Central Asian states, and Eastern European states like Belarus.
Step 1: Listing the Post-Soviet States.
The 15 states included Russia, Ukraine, Belarus, Kazakhstan, and others.
These countries were actual "Republics" within the Soviet Union's internal structure.
Step 2: Evaluating Poland's Status.
Poland was never a part of the USSR.
While Poland was a "satellite state" and part of the Soviet-led Warsaw Pact, it remained a separate sovereign nation (People's Republic of Poland) and was not one of the 15 republics that formed the USSR.