The more I read about Kiev rule the more I understand that corrupt policitians allowed for this to foster, Russia is simply taking advantage of an opportunity created from within Ukraine’s borders. Not that it makes it right, but clearly the raiding of the public’s money has contributed to the current situation.
Russians have been waiting for an opening since 1954.
I suspect there was some resentment towards Khrushchev’s handing over of Crimea to Ukraine, that contributed to his eventual removal.