Yeah but the Russians didn't declare war because of their demographics. In fact, if you ask them why this happened Putin gave a whole speech [0] on this when he sent the troops in, which can be neatly summarised:
> We are talking about what causes us particular concern and anxiety, about those fundamental threats that year after year, step by step, are rudely and unceremoniously created by irresponsible politicians in the West in relation to our country. I mean the expansion of the Nato bloc to the east, bringing its military infrastructure closer to Russian borders.
It isn't obvious that China is dealing with the same sort of pressures in East Asia.
They would still probably do it, mind you, but it would be a huge scandal and a subject of existential dread for Russian media and elites.
The fact that they've been stripping their NATO borders bare with barely anyone noticing or caring shows that nobody views the prospect of a NATO invasion as realistic. It was always a fig leaf.
(Although maybe there were scandals and I never heard of them. My exposure to Russian media is filtered through Western media. But I heard about other scandals and anxieties.)
> The fact that they've been stripping their NATO borders bare with barely anyone noticing or caring shows that nobody views the prospect of a NATO invasion as realistic.
Nobody has ever suggested that there was a prospect of a NATO invasion of Russia. That is crazy talk; it'd be the end of civilisation in the northern hemisphere. They aren't deploying troops to ward off a NATO invasion, that is what the ICBMs are for.
Right. But why is NATO "bringing military infrastructure closer to Russian borders" a concern to Russia if they aren't worried about a NATO invasion?
So what's really going on? Well, Putin said "rudely". Russia feels insulted because everybody wants to be in NATO, and nobody wants to be Russia's buddy... if you take Putin's words at face value.
If you don't, then I think Putin is terrified of Ukraine's revolution against a Russia-friendly leader. He doesn't want a western-friendly revolution in a culturally-Russian-adjacent country to succeed - there's too much chance that Russians might decide that they like the idea.
Because the major point of that infrastructure is to kill lots of Russians? It isn't hard to understand the motivations here, we've seen the US throw a massive hissy fit in the Cuban Missile crisis because of Soviet gear in Cuba and that was much more benign than a full military integration. And the US has a history dating back more than a century of tolerating no rival military powers in their hemisphere [0] let alone on their borders. There isn't anything to wonder at here - the Russians see their security interests as covering their border regions. In a display of outrageous hypocrisy the US also sees their security interests as also covering Russia's border region. Kremlin concern over this is hardly unexpected.
The way the Ukraine war has played out makes it pretty clear the Russians did have legitimate concerns. When the US invades Iraq with no moral justification, everyone moves on. When Russia invades Ukraine with no moral justification we see a similar response from most of the world ... except NATO that goes in and orchestrates what Wikipedia suggests are half a million casualties of the Russian armed forces [1].
Why might Russian military planners feel this is a threat? Because they can count corpses and they're not stupid. If you want to argue that they underestimated the threat NATO posed them in Ukraine and so Putin was lying that is one thing, but if so his propaganda happened to be truer to reality than he thought because he made a great point. NATO is out to get the Russians.