Do you understand what NATO is? It's a transnational nuclear military without accountability to any populace, that was originally helmed by hand-picked Nazis to create an anti-Russian nuclear first-strike capability. Russia's direct statement about invading Ukraine explicitly said that NATO activity on their border has become too threatening to ignore. The very first NATO exercise in Ukraine happened months before the Euromaidan coup and immediately after the coup NATO began war exercises including flying B-52s in the region and simulating an invasion of Kaliningrad.

As far as the USA not having rusted outdated weapons, I point you to the $1T project to upgrade the US nuclear arsenal that started with the sentinel system and immediately hit an 80% cost increase (https://www.wral.com/story/cost-of-modernizing-us-air-force-s-nuclear-missile-arsenal-increases-by-over-80/21516120/) and a timeline problem that puts the upgrade well beyond the service life of the current Minuteman system, which itself ran into failed test flights recently.

Not to mention the number of jets the US can't keep in the air.

Not to mention the fact that Russia has destroyed effectively 3 full Ukrainian militaries, first the stuff Ukraine had, then the first wave of American and European armor, and then the second wave of American and European armor, all while increasing its active duty count and increasing its military production capabilities.

The reason Russia is threatening nuclear escalation is because the US and NATO are the standing nuclear threat and they continue to use the logic of escalation instead of deescalation and every analyst can see this. You could see it too if you stop reading the propaganda rags and actually build yourself an understanding.