Intervening when an attacked nation is not covered by a US defense treaty - what criteria?

Thread inspired by the recent discussion of how Russia might invade Ukraine:

I think we’d pretty much all be in agreement that if a nation is covered by a US defense treaty, that the United States should intervene if they are attacked (i.e., a NATO ally being invaded by Russia, or South Korea being invaded by North Korea, etc.)

What gets much trickier is when some nation is not covered by any sort of U.S. defense treaty but is attacked by an adversary anyway. In the example of Iraq invading Kuwait, the U.S. went to bat for Kuwait, in the instance of Russia taking Crimea from Ukraine, not so much.

What sort of criteria should be met for the U.S. (or other nations) to go intervene when there isn’t an explicit defense pact?

The answer is the same for both, actually, treaty or no: the best interests of the United States.

I’d imagine the logic goes something like this:

I would prefer the US to not be the world’s policeman. To that end if we aren’t required to be involved with a conflict we should let the individual countries deal with it or at most other countries in the region.

In this case eastern Europe may get involved but if any of our allies do it would be without us.

Unless and until they are directly attacked, in which case the relevant treaty obligation would presumably apply, such as Article 5 in the case of NATO.

The counter argument to @Oredigger77 of course is that appeasing an aggressor by letting them have a few countries without a fight doesn’t actually defuse the threat they pose to the rest of the world. In fact it usually emboldens them to be more aggressive while at the same time demoralizing the allies you do have who happen to be in harm’s way.

“Vital interest” is a common term of art in the foreign policy game, but like any legalism, it doesn’t yield bright lines. Defending Afghanistan from the Soviet invasion wasn’t seen as a vital interest. Defending then-West Germany from a putative similar invasion was, NATO treaty obligations aside.

Ukraine, not coincidentally, is one of those very borderline cases that makes a very tempting target for a salami-slicing bully country like Putin’s Russia.

They don’t have to be appeased, there is the whole EU there, many of whom could drive to Ukraine in a couple of days. Why don’t they move 80,000 troops to Ukraine to counter the Russians? This looks like another European war, they should sort it out without relying on the US.

That’d be right.

International obligations ratified by Congress and the US decides action based on which one side has the more oil or WoMD.
The best interests of the US were precisely why you signed the treaty.

You don’t need to wonder why US standing has cratered and it wasn’t just the efforts of Dubya and Trump.

Agreed that in an ideal world the EU should lead in their backyard. But if they don’t, or don’t much, then the US is still faced with the decision: Leave the Russians to do as they will and the EU to respond as it can, or stick our nose in to change the outcome.

Yes, every time we do that we encourage EU free-riding. And every time we don’t do that we encourage Russian (and other bad actors’) adventurism. Like so much in human affairs (and therefore affairs of state) there are no good answers, only gradations of crappy answers.

I am not suggesting the US & Russia should wage full bore WWIII over Ukraine here in 2021/22. I am suggesting that simple grade school play yard ideas like “let the EU handle it themselves” aren’t simple; they’re simplistic.

Why is it a grade school idea? The EU touts itself as a world leader, let them show some leadership. Are you telling me that the 20 odd countries in Europe are incapable of deterring a Russian takeover of Ukraine? Of what use are they in NATO then? Theoretically, they have already been deterring the Russians for 75 years. A movement of some troops is well within their capability.

Europe has historically proven to be unable to deal with military aggression on their own.
Europe probably could have defeated Germany after Russia got into the war, by Russia would have owned all of Europe rather than just the East.

In other words, Russia (the USSR) could have defeated Germany. I don’t think that’s the type of “Europe” being discussed here.

As a military matter, NATO has always been the US and nobody else. The European members are there to provide political and diplomatic cover for whatever the US does under the banner of NATO.

My point being, that if the USA hadn’t fought in WWII, Europe would be part of the Soviet Union. Europe can’t go it alone without the USA as a NATO member. The USA is stuck with being the “Big Guy” in NATO.

The EU may or may not show “leadership” as you suggest. But the US needs to have a plan for whichever choice the EU makes. A plan that serves the US’s interests.

The thing Trump fundamentally failed to understand is that “enlightened long term self interest” is the goal. And often doing something that’s not immediately ideal for your most narrowly defined short term interests is in fact in your own long term interests properly understood.

Of course the US needs a plan. I’m saying Plan A should not include the US getting into a pissing contest with Russia over Ukraine while the EU sits idly in the background doing nothing. If Ukraine is important to them, they should have some skin in the game. Surely they can put together enough troops and political pressure from 20+ countries to counter the Russian troop movements.

Amen. The purpose of NATO is that the bad guys know that the US will back up the Europeans, who, as you point out, must have some skin in the game.

The old saying is that NATO was there to keep the Russians out, the Americans in and the Germans down. Since then the Germans have shown few signs of wanting to be up again, and even now that might still be sensitive for people to their east.

It was said that the way to become wealthy in West Germany was to buy an acre of land and wait for an F-104 to crash on it.