> but I really can't picture a scenario that leads to another world war, even in today's relatively unstable political climate.
Ten years ago I bet almost no-one was picturing the late-1980s anti-nuclear treaties going the way of the Dodo bird. Or a land war in Europe (Ukraine is indeed in Europe). Or German politicians being shot for their political beliefs. Or British politicians being shot for their political beliefs. Ten years ago I wasn't seeing US soldiers and their trucks almost every time I take the highway in order to visit my parents in the countryside (I live in an Eastern-European country and NATO member, a geo-political stone's thrown away from Russia). Ten years ago Russia wasn't testing a nuclear-fueled rocket.
Assuming you're talking about the US pulling out of the INF treaty, that's not really a meaningful change. The Russians and various other countries were already largely ignoring it. Russia's territorial shenanigans are what really cemented the idea that we're not fighting a major super-power to super-power war ever again. The West has largely let it happen, and while I don't understand why, at this point it's hard to see why that would change. US troops have been in Europe for a long time. Whether you saw them more or less in the past, troop levels there haven't changed that much.
They haven't been in Romania, which is, like I said, a stone-throw away from Russia. And they started showing up after the start of the conflict in Ukraine.
> Assuming you're talking about the US pulling out of the INF treaty, that's not really a meaningful change. The Russians and various other countries were already largely ignoring it.
That's not my understanding of it, at least not when it involves Russia (China is another story).
> Russia's territorial shenanigans are what really cemented the idea that we're not fighting a major super-power to super-power war ever again
Not sure how that follows. When you have nuclear weapons that you can launch from anywhere at anytime you are a super-power. The US and Russia are 100% military super-powers because they can basically annihilate each other at a moment's notice. I'd add China to the list, probably the UK and France too (not sure if France has nuclear submarines, though, too lazy to check right now). Even though Israel has nuclear weapons I don't treat it as a military super-power because of its lack of nuclear submarines or IBCMs. The same goes for Pakistan and India.
https://www.globalsecurity.org/military/facility/romania.htm
They have been, in fact.