[mewpmewp2]

These are the "excuses" by Russia. The only real motivation is to expand its own power and influence in the World. They will find whatever lowest hanging fruit to justify the actions they think will lead to it. They will try to propose a rhetoric that sounds as if they are justified to something. Everyone does that, not just Russia, but there are countries and leaders who always want to expand at the cost of others, and there are countries who just want to be and are fine with their borders. If it wasn't decade old broken promises by someone from NATO or whatever they would of course dig for another reason as part of the propaganda. There is no rational reason for a peaceful country without goals of expansion to fear NATO. They don't like the expansion of NATO because it limits their abilities in the future to expand.

NATO is for countries that want to stay as they are without having to be as scared that Russia decides they would be their next target for expansion. If those countries in the east didn't join NATO, Russia would use another excuse to at first opportunity invade and occupy those countries.