What country is most closely related to the soviet union

Answer is Russia.

Russia is most closely associated with the Soviet Union because it was the largest , most powerful and most influential of all the republics that made up the Soviet Union. It was Russia that created the Soviet Union when Vladimir Lenin had Russia join with Ukraine, Belorussia and the Transcaucasus Federation to create the Soviet Union in December 1922. Many people erroneously think that the Soviet Union is simply another name for Russia. It is not.

Russia used to be the Soviet Union simple