Brief summary: according to Americans, everyone else is doomed if Americans walk away.
Er, no. If America walks away, that's when America discovers everyone can manage perfectly well without them, just like we did the last time y'all had that orange muppet in the Shite House.
I'm the first to agree usually, USA Defaultism and such is a huge annoyance.
But, while the following is just one theory, it was plausible enough to give me pause, and consider that there may be avenues for things to go badly that I wouldn't have thought of otherwise.
This scenario doesn't include the USA leaving NATO but instead not responding to Article 5 if it's triggered in an unimportant backwater corner of NATO, so functionally it's the same kinda idea.
So, according to your comment Europe is getting free (military) resources and/or money from the US with no agenda or gain for the US?
It's like "The US (alone, for your clarification) against the World, we do things just to empower every other nation and everyone else".
Please, bring your guys home, then.
Maybe the World would be better off.
Can we stop talking like using nukes could somehow be reasonable. The thought of using a first strike nuke should be considered beyond outrageous and any leader that even remotely considers it should be ran far away from any position of authority.
Nobody in their right mind considers it. It's just a global game of chicken, and some weird armchair strategists try to convince everyone that nuclear attacks are basically the first option on the table.
And I sometimes suspect, that this sentiment gets pushed by Russia (not created, but pushed), because the western fear of nuclear war is definitely an argument against delivering weapons. Especially here in Germany, literally every single new weapon system was considered to "cross a line", so Russia might attack if we send it.