Like I said, you're assuming the US gives a shit. The Cold War ended a while ago, the last Cold War generation is aging into retirement. Europe/Russia is now a secondary concern in the US next to China. NATO blowing up would destroy American diplomatic credibility, but we've already kinda done that in multiple ways over the last few years, and our military is still more than potent enough to look after our interests.

Granted Russia is still seen as an adversary, but if Russia manages to quickly steamroll the Balkans/Poland/Ukraine and then challenges NATO to do something about it, I'm not sure there's the stomach for a bloody, protracted invasion of the continent to reclaim the lost members.

There's also a large swath of the US that sees NATO as a waste of US time/money, with members that largely don't pull their weight and are just mooching off the US, hell that was part of Trump's platform. And Secretary Gates under Obama complained, more diplomatically, about the same thing.

There's a substantial chance that a Russian invasion of any part of Europe would be seen as a "European problem" by a large chunk of Americans. None of this is to say I support that position, but that's where we're at IMO. America is largely turning inward for the first time since WWII, the question is whether Europe will figure that out before Putin does.

USA will have to give a shit for one reason: the war against Baltics or Poland is the war against whole Europe. Germany will not stay away and observe, as will not do France or Italy. EU is the largest trade partner of USA, the biggest market for its exports etc. Regardless of the strategic games in the Pacific, USA cannot afford to lose it or to allow it to be devastated by a big war.

I am all for international trade. But can we let the European countries grow up and provide their own defense? USA can't really afford another decade of aggressive military meddling. Deficits are running away from any plausibly realistic plan to balance spending and tax receipts, so we are economically killing our future.

Grow up? US used NATO article 5 to get European NATO partners to join US wars in the middle east. The soldiers went there and died in US conflicts to help you with your ”war on terror”.

How about pay your fucking debt and keep Russia at bay.