In the UK, it is VE day today. It will be celebrated in Russia tomorrow, and it will be interesting to see if the parade is disrupted or not.
I was to make a post about NATO expansion and the promise not to do so, and I still will, but before I get onto that, Putin has said that Romania and Bulgaria are partly to blame for his invasion of Ukraine. This is in part linked to the issue of NATO expansion. Apparently, there was a verbal agreement made that NATO would not expand after the unification of Germany. As you can see from the video's below, there is a lot of evidence to back this up.
But after that verbal agreement was made, Russia invaded Moldova to liberate Transnistria in 1992 and the following year, invaded Georgia to liberate Abkhazia. To be fair, to Russia, violence had erupted before the two invasions, that in Abkhazia being especially brutal. The invasions did bring about peace, but they also in effect have expanded Russian territory to include areas with Russian speaking people.
NATO expansion did not take place until after the two invasions, Poland calling for it in 1993, but not being admitted until 1999 when Hungary and the Czech Republic also joined the alliance.
So yes, Russia did think it had an agreement that NATO would not expand. Russia then caused nations to want to join NATO by invading (and still occupying) parts of Georgia and Moldova.