RJM, firsly: NATO expansion took place in 1997. Plenty of time since then to invade Russia if that were the plan.

2ndly: The persons you mention could not speak on behalf of NATO, and such "security assurances" were never put into treaties. Instead, there were several non-stationing agreements signed between NATO and Russia, some of which are still in force (formally), which are a good safeguard against sudden attacks.

Finally: If Russia were in fear of NATO aggression, they would have objected against Finland joining.

The bottom line is that Putin wanted to reserve the right to annex or dominate all countries in its claimed "sphere of interest", in blatant breach of the UN Charter etc. (Indeed, other countries may want the same, thus it must be counteracted all the more resolutely.)

These countries include the entire former SU, Warsaw Pact states, then all earlier Russian conquests including Finland (!) and Alaska (!).

Weapons alone do not suffice against such claims. We must debunk the propaganda myths whenever we see them. Russian people can read and have access to the Internet. Write good songs that help them (and us) to get rid of the régime.