I feel Putin is using NATO expansion as a convenience to create an imaginary foreign threat and scapegoat, similar to Cuban rhetoric of the trade embargo. The way Putin talks and the propaganda he puts out, he wants Russians to believe some sort of NATO attack on Russia is a real threat when of course it is not. One of my favorite ww2 movies is a brilliant Russian propaganda piece named "White Tiger". It's message is the threat of fascist invasion will always exist and must be prepared for. It's actually free on YouTube:
https://youtu.be/qiGDJ5-dXaI
In the early 90's there were discussions to have Russia join the alliance, something Yeltsin wasn't necessarily opposed to.