I would say that cultures interact in much the same way individuals do. In both cases there are things like exchange, mutual cooperation, conflict, argument, persuasion, and coercion.

True. What I would be saying, analogously, is that we have taken the "you-do-you while I-do-me" principle too far: if your friend decides to go out and rape someone, then you have a duty to forceably impose your values on them insofar as they shouldn't be doing that. Similarly, a society has a duty to take over or at least subjugate another society to their values when the latter gets too immoral.

Anti-imperialism is a very limited justification in the first place. But the disorderedness of a society is not in itself a sufficient reason for intervention. Should we intervene in North Korea out of compassion? Perhaps, but perhaps not. Compassion can be a motive, but it is seldom a sufficient condition for action.

Even if the negative consequences were very low (or non-existent), are you saying that the West would not be justified in taking over North Korea by force?

I agree that coercion should be the last resort, but it seems to be a resort; and seems to be a valid resort to stop societal structures that are really immoral; and this entails some version of imperialism, even if it is a much weaker version than the standard ones historically.

What I would be saying, analogously, is that we have taken the "you-do-you while I-do-me" principle too far: if your friend decides to go out and rape someone, then you have a duty to forceably impose your values on them insofar as they shouldn't be doing that. Similarly, a society has a duty to take over or at least subjugate another society to their values when the latter gets too immoral.

...

and [coercion] seems to be a valid resort to stop societal structures that are really immoral; and this entails some version of imperialism — Bob Ross

Well, in virtue of what do we have a duty to prevent immorality? Do we have a duty to perpetrators? Do we have a duty to victims? Do we have a duty to "friends"? Do we have a duty to strangers? Do we have a duty to strangers on the other side of the world?

Even if the negative consequences were very low (or non-existent), are you saying that the West would not be justified in taking over North Korea by force? — Bob Ross

If there were no negative consequences then we would be justified. But even something as simple as resource allocation is a negative consequence, so there will always be negative consequences.

Even if the negative consequences were very low (or non-existent), are you saying that the West would not be justified in taking over North Korea by force?

I agree that coercion should be the last resort, but it seems to be a resort; and seems to be a valid resort to stop societal structures that are really immoral; and this entails some version of imperialism, even if it is a much weaker version than the standard ones historically. — Bob Ross

When both the US and North Korea have nuclear weapons, then the question would this:

How many Americans and what percentage of North Koreans population is a justifiable sacrifice to erase the North Korean dictatorship out of existence? And if with Americans the death toll less than have died of Covid (less than 1,2 million), let's say just Hawaii and the Bay area were destroyed, then how many North Koreans would it be enough to revenge the lost Americans?

Well, in virtue of what do we have a duty to prevent immorality?

Justice—no?

Do we have a duty to perpetrators?

What do you mean?

Do we have a duty to victims?

Yes. To punish the perpetrator and avenge the victim(s).

Do we have a duty to "friends"?

Yes.

Do we have a duty to strangers?

Yes. Do you not believe that you have any duty to be just to strangers?

Do we have a duty to strangers on the other side of the world?

Does being just ultimately depend on where the injustice is happening? Sure, circumstances matter, but, in principle, it doesn’t matter.

If there were no negative consequences then we would be justified. But even something as simple as resource allocation is a negative consequence, so there will always be negative consequences.

Agreed.

We are not justified in going to nuclear war with North Korea, assuming both sides have working nukes, to save the people there. The nation firstly has a duty to its own citizens, and not other citizens of other nations.

Justice—no?

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Yes. To punish the perpetrator and avenge the victim(s). — Bob Ross

Generally we do not believe that everyone has legal standing (locus standi).

Similarly, it is the duty of the judge to punish the perpetrator and avenge the victim, not the common person.

Do we have a duty in justice to right wrongs happening on the other side of the world? I don't know. Maybe, but not really? Not everything is within our jurisdiction. Here is Aquinas:

Again, no man justly punishes another, except one who is subject to his jurisdiction. Therefore it is not lawful for a man to strike another, unless he have some power over the one whom he strikes. And since the child is subject to the power of the parent, and the slave to the power of his master, a parent can lawfully strike his child, and a master his slave that instruction may be enforced by correction. — Aquinas, ST II-II.65.2

Generally we do not believe that everyone has legal standing (locus standi).

I think moral and legal standing are different: the latter is a practical attempt at justice for the community, whereas the former can surpass that sphere of jurisdiction. To deny this, by my lights, is to accept that nothing immoral is happening, e.g., when a citizen of another country violently attacks a citizen of another (for there is no notion of justice qua morality in this sphere of discourse since it lands outside of the purview of both societies to a sufficient extent).

Perhaps the solution is to say that both authorities of each society would congregate to resolve the matter, as opposed to the lower institutions (e.g., police) imposing justice; but, then, what of the, e.g., indigenous member of the tribe, which does not have a sufficiently powerful community to advocate on their behalf, or the non-citizen? Are they chopped liver? If there is not such distinction, mentioned above, then I think so.

Similarly, it is the duty of the judge to punish the perpetrator and avenge the victim, not the common person.

This is true if we are careful to denote this duty as legal duty—not moral duty. E.g., I do not have a legal duty to save my daughter from a burning building but I certainly have a moral duty to do so.

Usually, when we note that a person doesn’t have “duty” to enact justice for another; we tend to be saying that as a pragmatic rule of thumb for two reasons: the first being that it tends to be handled more appropriately by those that are of an institution designed to handle it (e.g., police, first responders, etc.), and secondly because imposing that justice usually has sufficiently negative consequences to the avenger that we would not blame them for avoiding avenging or stopping the attack in the first place.

However, I do think it is commonly accepted that if the negative consequences are sufficiently trivial, that it is immoral to do nothing. For example, the man that watched this women get kidnapped while she screamed for help technically doesn’t have a legal duty to intervene; but we all think he should have (morally speaking, as that is a part of a man’s moral duty and role in society to be a protector).

Do we have a duty in justice to right wrongs happening on the other side of the world?

The problem I have with this line of thinking is that, in principle, we can wipe our hands clean when we avoid doing just things because they are outside of our jurisdiction—jurisdiction is just a pragmatic notion to enact justice.

Likewise, the issue with thinking solely in terms of jurisdiction, in the sense Aquinas noted in your quote, is demonstrated sufficiently in the quote itself:

And since the child is subject to the power of the parent, and the slave to the power of his master, a parent can lawfully strike his child, and a master his slave that instruction may be enforced by correction

People who think in terms of solely jurisdiction have the same susceptibility as denotoligists: avoiding the right thing to do because it doesn’t follow the strict rules laid out for people to follow by people.