Bob, Bob, Bob. Your position is such a jumble.

Maybe you thought to yourself, why don't we do more to oppose tyranny throughout the world? Why do we allow people to be oppressed by their own governments?

-- But, interrupted skeptical Bob, on what grounds would we oppose tyranny?

Democracy! Our values!

But then you realized this is trouble: a core democratic value is tolerance.

Which is fine, you thought, except people take it too far, allow themselves to be paralyzed by a mamby-pamby cultural relativism.

We've become like people who *say* they have religion, but don't want to convert anyone.

Well do we believe in democracy or don't we? If we do, let's act like it! Let's go convert some mofos.

-- Just because we believe? asks skeptical Bob.

Hell yeah! We believe, and if we really believe that's enough.

And if others believe something else, let them try too. Every country should act on whatever it believes, because ..., because ...

Because we can't give in ...

to relativism.

There is no 'objective' realism.

That’s your problem: you aren’t a moral realist.

For example, if the Nazis stayed in Germany (in the sense of not invading other countries), then would you say that no country should have invaded Germany to stop the Holocaust? — Bob Ross
No country did; most wouldn't even take in refugees.

You didn’t answer the question; and provided, instead, a red herring. I will ask again but with more clarity: if the Nazis stayed in Germany (in the sense of not invading other countries), then would you say that no country is justified in invading Germany to stop the Holocaust?

Who "we"?

Ideally, the Western, modern world. Now, is it feasible for everyone to band together in the name of the human good? Probably not.

You read this in history, or tea leaves? How else do you get the majority of a people to volunteer for extreme hardship and danger, for the purpose of imposing one government's will on another?

In the name of the human good, or at least what is good. Most people would understand how it would be justified to conquer the Nazis to stop the Holocaust; but, to your point, many people would be too cowardly to act.

He wasn't alone; the regime was brutal. He reported to Ferdinand II and had the use of soldiers, administrators, overseers and priests sent by the monarch. Is there any record of the common people of Spain or Portugal clamouring to bring civilization to the Americas? D you truly believe they would have voted for the conquests on moral grounds?

The way they handled the conquest of abhorrent; because they were not trying to help the people there: they were wanting world domination. Imperialism is not identical with national world domination.

What the OP is referring to by imperialism, is its simple form of a nation having a duty, under such-and-such circumstances, to conquer and impose their values onto another nation (without it being legitimate self-defense or something like that).

Again - both pre-WW2 Germany and today's North Korea have or had formidable militaries - North Korea has nuclear weapons.

Correct, but that’s despite the point. I am saying that, in principle, you would have to reject the west invading the Nazis, or North Korea, or China, even if it were easily possible to do—because you are against imperialism.

Whether or not, in practicality, it is possible to do so is irrelevant to my point right now.

Has a military intervention to protect tyrannized people ever worked?

It was in Afghanistan until the US got out. Al Qauda was eradicated and the Taliban was suppressed; but then the US left and the Taliban took power (again).