All of this talk about "Russia being frightened by continual NATO expansion" is nonsense. Basically, it all comes from one of Uchicago's less talented professors; this fellow named John Mearsheimer. And Mearsheimer is a senile guy who came up with a set of talking points 14 years ago and has not been able to drop them. People hear his educated sounding spiel and then don't bother to look up the details behind exactly how NATO has expanded.
I will save you the effort. Here are those details. They do not fit very smoothly into Mearsheimer’s story.
Until Finland and Sweden sought out membership because of Putin's invasion of Ukraine, there had only been two new member states added since 2009: Montenegro and North Macedonia.
Tremble in fear, motherfuckers, at these powerful additions to NATO. I mean, how could Putin have not been terrified at the prospect of an army of Montenegrins and North Macedonians overwhelming the Russian steppe just as the Mongolian hordes did centuries ago. Nuclear weapons can never deter such a force, I am sure.
The real causes of the war are the following:
1) Crimea's access to water from the North Crimean Canal
2) The creation of a land bridge to Crimea
3) The fate of the Donbas Republics (which Putin encouraged to rebel because of their large Russian speaking population and to create a land bridge to Crimea).
4) The discovery of natural gas and oil reserves in Ukraine that would reduce Putin's leverage over Europe.
5) Simple Irredentism
6) Putin was losing his grip on power and thought a quick military victory would allow him to rebalance the power dynamic in the Kremlin.
7 ) Mystical ideas about Kiev being the "origin and spiritual homeland of Russia."
8) Fear that a successful democracy to his South that had joined the EU would strengthen the hand of Putin's liberalizing opponents.
In fact, when Putin speaks of this being “a war of survival against the West” what he really means is that it is a war to prevent Russia and Ukraine from developing closer ties to the EU, which Putin believes would deny Russia the authoritarian leadership it needs to maintain its cultural identity. If you look very carefully at what Putin says, and the talking points he likes to throw to the likes of Jordan Peterson, it becomes clear that this might be Putin’s most important motive.
When Finland applied for NATO membership, they took no action to deter them from joining. Putin could have massed troops on Finland’s border, stepped up patrols in the Baltic, and placed more pressure on Turkey to block their membership. Instead Putin did nothing—if anything, he seemed not to care.
EU expansion might have been a factor. NATO expansion was not.