Perhaps not Belgium, but consider eastern Ukraine.
The US is looking to disengage as much as possible from global conflicts. I think that they would be extremely reluctant to be pulled into a head on war against Russia/ China over a lot of 3rd countries.
Putin is deliberately isolating conflict regions from each other and from the bigger picture, somehow hoping that no single attack is worth it for NATO to actually retaliate in any form. So far, as long as no NATO countries are in immediate danger, this works extremely well.
An example could be nuking a large staging area or aircraft carriers. There's nothing irrational about it, once war progresses this far.
The premise is that when the Soviets decided to invade they'd lob a few of these at their forces and pin them down for a little while, so the rest of NATO could mobilize.
It seems that even at that time, the US wanted to keep the conflict nuclear-free as much as possible.
(I'm French, just stating)
These cities changed hands every 50 years or less for last few centuries. It's useless to argue about these things.
Basically whole C&E Europe is a huge barrel of powder. If you start to do this stuff (this is MINE because history) the powder will explode.
That's why nobody (except Russia) do it. Even the worst nationalists in Poland don't actually want L'viv or Vilnius. Even though L'viv was a very important city for Polish culture and still 80 years later there are songs about how great a city Lwów was (French wouldn't understand, you only have one city ;) ). It was Polish San Francisco, and we don't want it back.
That's because we know that we are only safe because we're past the WW2 era of petty nationalisms. We've learnt our lesson.
Putin doesn't care - he knows EU is not united enough to react, so he basically replays Hitler 1938 strategy and he goes away with it. French traditionally don't want to die for Danzig(Donetsk this time), they even sell weapons to Putin. Great job, guys.
It's very frustrating to see it in real life and see how useless and clueless western politicians are. Like nobody learnt anything from WW2.
Before 1783 Crimea was part of Ottoman Empire (Crimean Khanate), from about 1449. That makes 334 years.
And before that Mongols ruled there from about 200 years.
And even before it belonged partly to Kiev Rus' and Bizantium for another 300 years.
So basing solely on the years (assuming that what you mean by historically) it looks like Crimea should go back to Turkey or split between Ukraine and Greece, surly not to Russia.