The story goes back to the year 2006 when the “West” declared the initiation of the process to include Ukraine and Georgia in NATO. Russians were always against the expansion of NATO as it sees it as an existential threat to its sovereignty. Till 2008, Russians explicitly started talking about the threat of NATO’s expansion.

A coup supported by the U.S. in 2014 resulted in pro-Russian leader President Yanukovych being overthrown and replaced by a pro-U.S. leader. The West tried its best to even a single Russian presence and put in effect the Orange revolution.
To this, Russians responded by helping foster a civil war in eastern Ukraine. Kremlin made it unequivocally clear that the expansion of NATO was an existential threat to them. To America’s surprise, Russians captured the Crimean Peninsula and showed signs of reaction.
By 2017, the U.S. started arming the Ukrainians and forming ever closer diplomatic ties. The tipping point was about to be reached and as Lavrov said, “The boiling point was reached.” And on 24 February, 2022, Russia invaded Ukraine.
The opposing argument we hear is that it has nothing to do with NATO’s expansion but is a result of Vladimir Putin being bent on recreating the Soviet Union and expanding to the West. But before this crisis, NATO, as we all know, was a hibernating giant and nobody argued against expanding NATO to counter Russia’s expansion.

Russia doesn’t have enough economic resources to take on the West in a war as it’s not the old gold days of the Soviet Union. Occupying Ukraine and eastern Europe would be like “swallowing a porcupine”.
If we look at the nature of the war, it is clear that Kremlin is not looking to control or conquer Ukraine. Instead, it will try to create a buffer state and establish a pro-Russian regime east of the Dnepr river, which flows through the capital covering the eastern part of Ukraine. Ukraine is more important to Russia than to the U.S. So, Russians will prevail as the balance of resolves favours them.
On the other hand, the West has made Ukrainians fight the war and pushed very hard to make them a western bulwark on the Russian border. From all this, it’s the Ukrainians who suffered and in reality, it will tear apart Ukraine.
I conclude that the West triggered the latest security dilemma of Russia by the expansion of NATO and EU.