Hm, I guess we're talking past each other: As far as I can tell, we already agree on the fundamentals of this issue: The US military is too big, military action is often, but not always a bad thing, conflict prevention and development aid are preferrable to military action, etc etc.
Maybe it's a cultural issue: When a German talks like you do, they usually espouse some sort of vulgar pacifism, usually accompanied by a big helping of anti-Americanism and NIMBYism. And I guess when an American talks like I do, they're usually Republican and quite far on the hawkish side.
Maybe we should just skip ahead to the specifics: When do you consider military intervention to be desirable or even just justifiable?
Maybe, yeah. Ideologically, I
am a pacifist... but not a strict one. I believe that the nature of violence varies according to scale, and I fundamentally disagree with the nature of large scale violence. I started to type out an explanation but it's probably best not to get into the details of that now.
What's important in relation to what you're saying is I also understand it's necessary to concede the reality that ideologies don't amount to much when most of the world doesn't share them. We have to survive within the reality that is created by the collective behaviors of other people, even if we believe those people are stupid and wrong.
When do I consider military intervention to be desirable or justifiable?...
Short answer: Only blanket response I can give is in the clearest cases of a situation violently out of control, and a clearly delineated group being primarily responsible for that. Only military engagement by the U.S. I'm aware of that I'm alright with since WW2 is the intervention in Libya. Even if the aftermath hasn't turned out to be a good political situation, there was no question that Gaddafi had gone completely insane and was going to continue indiscriminately mass-murdering his own people until somebody stopped him.
Long answer: I know that military involvement is really justified and desirable in a lot more situations than that, but outside of such situations, there are so many nuanced factors that I can't really give an answer to your question as stated. I can tell you that the reason I'm not alright with most U.S. applications of military power is because there are too many corrupting influences involved, too little restraint, and they are not balanced against other approaches that would suit our professed intentions. But it sounds like you already agree with that. Problem is this is such a deep and pervasive facet of U.S. politics that it's hard to express this point of view without coming off as rabidly anti-American.