Two things. One is that we should maybe think about why, in spite of the risks of provoking Putin that many people are highlighting, Eastern European countries wanted to join NATO anyway. I assume they knew the risks very well, but thought it was still safer than not joining. If NATO doesn't let them join, it sends a message to Putin: we don't care about these countries and won't protect them. That's what he thought was the case with Ukraine, and we can see how that's working out.
Two, the "encircled by NATO" thing is not all that's going on. Putin has a set of ideological beliefs that are driving his actions as well.
https://www.nybooks.com/daily/2018/0...ssian-fascism/
Ted