No pain is ever irrelevant. But it is mostly unavoidable.
If you truly desire the US - or any other country, for that matter - to take a foreign policy stance which doesn't favour some over others, then you will be sorely disappointed. It doesn't matter what any state does in the world, every single one of their actions is going to leave a big "what if" dangling overhead as people wonder what the alternative outcome could have been.
"Maybe if the US hadn't invaded Afghanistan thousands of lives would have been saved and the world would have been different. Or maybe al-Qaeda would have struck again and thousands more would have been killed." The simple fact is we do not know what would have happened in the alternative. It may have been better. It may have been worse.
So for you to deride the US' actions as leaving a lot of pain in their wake, fundamentally assumes that if they hadn't done what they did, this pain would have been spared, and yet you have absolutely no way of knowing the alternative. Ironic, given you pointed out my slippery slope argument.
On another note, I would much prefer the democratic government of the United States having unilateral international power than China, Russia or most other aspiring superpowers.
And you'd be an idiot if you didn't dispute them.
But just because the US isn't perfect doesn't mean it's not ahead of the competition south of the Rio Grande.
I never said that the US was justified in it's actions. I simply said that it's power projection was perfectly understandable given it's economic, political and military weight and that I would personally prefer the US in this position than most other powers.
Now, some may assume that I meant it is justified, but this in turn begs the question of it being justified by what means?
On humanitarian grounds, it is certainly not, but humanitarianism far too often involves a degree of selflessness on the part of certain parties which is entirely unrealistic.
If instead you meant that the continual intervention of the United States is justified by Realpolitik considerations, then by all means, it truly is.
As for the rights and responsibilities of states on the international stage, I'm afraid you are very much mistaken here. The simple fact is there are no such thing as rights and responsibilities between states, only mutual self-interest which so happens to occasionally intersect and demand cooperation.
If there are indeed certain rights which states have, they must either be natural/universal or legal/civil rights. They are not the former, simply because the modern state is not a natural construct but a man-made social creation for the organisation of a population and therefore cannot have natural rights. Nor are they the latter, as this imples there is some higher power which can give these rights to the states, of which there is none (I'm ignoring theocracies here for obvious argumentative reasons).
Furthermore, there are no such thing as responsibilities of states towards each other, simply because there is neither a guiding moral principle to their works, nor an overseeing body to force these responsibilities onto the states.
