Putin just said it's a consequence of Lenin creating the fake entity of Ukraine on territory that should be Russian exacerbated by Stalin transferring additional territory that should be Russian to the fake entity of Ukraine.
Sounds like Russia (or at least Putin, who definitely has a l’etat, c’est moi thing going on), thinks the fundamental problem is the fall of the Russian Empire, not NATO, which is just an impediment to restoring the Empire.
