Putin was not in power in 1994 or 1997, and that appears to be the last time they agreed to a NATO expansion. Those were the Yeltsin years, and treating the Yeltsin and Putin administrations as though they are the same is like treating the Obama and Trump administrations as though they are the same. Enlargement of NATO kicked into high gear in the early 2000's, and Putin himself has cited NATO expansionism as a reason for this war (as well as the Georgia war and the 2014 Crimea war).

https://en.wikipedia.org/wiki/Enlargement_of_NATO

There is no serious analyst on this situation who thinks NATO expansion isn't at least a factor, if not the primary cause.