These people have experienced being part of ussr and really, really don’t want to go back. Source: am Eastern European

Russia isn't part of USSR either. Source: am Russian

No, Russia isn't part of the USSR any more: It's all that's left of it.[1] Source: am not Russian

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[1]: But, hey, don't despair: Belarus will join in any day now.

Putin wishes it still was.

Putin is not thinking about the USSR. He's not a communist and he is not interested in a soviet union.

He is thinking about the pre-Tsarist Russian Empire. Which included a few countries that were not in the USSR.

AFAICS, it's all the same to him: If he were dreaming only of reviving the Tsarist (why "pre-"?) Russian Empire and not the Soviet Union, he'd hardly have gone on the record saying "the fall of the Soviet Union was the greatest geopolitical tragedy of thetwentieth century".