Hard to separate politics from this situation.
Russia is merely protecting its economic and military interests from the very real threat that those interests would be compromised by the disintegrating situation in Ukraine. If Maine had seceded from the US 20 years ago, but (i) we still kept a large portion of our Atlantic fleet there, (ii) had tens of billions of dollars invested in oil/gas pipeline infrastruture still running through Maine, and (iii) Maine was still 60+% ethnic Americans, we would absolutely put troops on the ground in Bangor. People would go nuts if we didnt.
Hey false equivalency Butthead, you'll have to remind me of the time a hundred years ago when the US conquered Maine and then returned its independence twenty years ago.