People love to cry foul when the US flexes it's might... then cry foul when the US takes a back seat... literally cry foul no matter what the US does.
If Ukraine is so important to the world order, why has Europe (you know, Ukraine's actual neighbors) not stepped up with their full military power? Why is Europe not threatening troops, missiles, aircraft, tanks, etc... even nuclear obliteration if Putin doesn't yield? Why is it the US has to swoop in, from half a world away, and save the day (again, and again, and again...)?
The US is not currently willing to send our citizens to die in Ukraine. Maybe Europeans should?
The US is currently not wanting Ukraine to win for a single reason - it’s personal to Trump. So much has happened that we’ve collectively forgotten that it was Zelensky said “No” to Trump on the phone when wanting to find any dirt on Joe Biden helping Hunter in business deals.
That totally explains why Biden kept slow-walking support packages...
It certainly will when Putin moves on to invading Poland or Finland. The whole point of holding the line at Ukraine is because everyone believes Putin won’t stop there.
"Putin is too sensible to invade Ukraine" was the argument people were making the day before he did. My guess is these are the same people who now say "Putin would never invade Poland".
Never been to Finland so no opinion on that.
Article 5 of NATO (an attack on one is an attack on all) has only been invoked once, by the US. So why did NATO members send their militaries to Afghanistan?
The real reason is that most conflicts never happen. Or are resolved before ending in a full war. Either the US or a European NATO country sending in troops would muddy the conflict so much that the risk of escalation is huge.
There's a difference between the US invading Iraq and US aiding a country being invaded.
Why can't the Germans send troops into Ukraine? Or the Brits (for all their grandstanding and bluster)?
Why must it be the US?
If "everyone" thinks Putin isn't going to stop with Ukraine, then it would seem Europe has an existential crisis to deal with - not the US, thousands of miles away...
Two reasons:
1. Because whichever country does go in, it gives everyone else in NATO an excuse to do nothing in response to Russia subsequently going to full war with whoever it was that went in. Strategic vs tactical response in local political sphere, short-term tactical benefit of using such an excuse comes at long term strategic cost.
2. Right now, each individual European power is in a state of "Oh no, Russia's probably 3-5 years away from attacking us if Ukraine falls, and it will take us 5-8 years to be ready to defend ourselves". The UK, for example, has a 136k active and 32k reserve personnel in total, while Ukraine forces have suffered ~400k wounded and ~50-100k fatalities.
Both points become "we can only intervene directly as a joint act from multiple nations".
That said, if the USA were to leave NATO, I wouldn't be overly surprised if rest of NATO may issue a joint declaration that Ukraine is now under their combined protection, nor would I be overly surprised by an alternative outcome such as NATO being functionally replaced with Article 42 of the Treaty on European Union: https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=celex%3A...
Even a non-nuclear direct conventional war would get very messy very quickly. NATO would have to seize Kaliningrad and Belarus, start interning Russian nationals, rush forces to hold the Baltic states, and so on. It's not complicated to say "this will be very expensive and deadly, so we're not going to do it unless absolutely forced to".
European states are now re-arming (the irony of fate is that it's now US policy for Germany and Japan to re-arm), but that is going to take a while.
If Putin wins in Ukraine, it will show everyone that the US is incapable to hold even a weak enemy such as Russia to account. It is irrelvant that you frame it as a choice rather than a failure.
Europe has been doing more than the US in absolute and relative terms to prop up Ukraine but it hasn't been enough to help Ukraine win. As a European, I would want our governments to put soldiers down and end the war, but Russia has been successful in the information war to make too many citizens afraid to enter with troops.
The US hasn't been saving the day for anyone without ulterior motives for a long time (ever?). You make it seem like it were generous moves to counter mostly Russia or e.g. ensure access to middle eastern oil.
The US has never spend money on its allies which it didn't believe has a large return. So the current Republican administration's view to reduce engagement is actually hurting themselves. Classic lose-lose.
"Peacekeepers" is obviously meaningless when there is no peace to keep, so the question is what happens when NATO troops attack Russian troops directly.