If we’re talking war - Annexation of Greenland would probably do it.

Once you piss off enough people with allies then historically a lot of contractual responsibilities kick in… But the new playbook like what we’ve we’ve seen in Israel is "as long as nobody in government says the word ‘genocide’ we don’t have to honor our previously signed responsibility to step in so even that’s dodgy.

Once the US is seen as enough threat to the sovereignty of other nations who are just doing their own thing I think the response will kick in. Right now other countries are likely going to target the US’s pocketbook by decreeing various economic and banking sanctions and ratchet up the internal pressures. The US correcting it’s own listing ship through internal citizen lead processes is the good outcome and letting it basically fall into civil war is a more acceptable outcome than outside intervention from an international law perspective.

The US has a lot of Hard power : economic development and money, millitary might, strategic bases the world over, an uncomfortable amount of the world’s nukes and a landmass that is legit difficult to wage a war on. The bar to actually interfering directly through boots on the ground intelligence related action is really high.