All sorts of stories told over the intent of Putin's invasion but the most credible comes from the man who knew Putin more than anyone and prob the best Russian politician of all time. Boris Nemtsov was Yeltsyn's preferred successor but Putin forced Yeltsyn and ignited the imperial sentiment to become the president in 1999.
In a Moscow rally in 2015 Nemtsov said "Putin is a sick man, he will invade Ukraine no matter what, Russian's will come home in body-bags and Russia will become Ukraine's eternal enemy".