There is already a group like that within the US military: Special Forces. And to a certain degree, the Operations division of the CIA. Neither of these approach what you're describing here (if I'm reading your words right) -- and so I think there's room for improvement -- but the seeds for that are already a high priority for our (US) military.

Agreed there's a trend in that direction, but as you say not quite there yet. What I imagine is a unit with the goal of helping civilians as a first priority, but with the full capability to defend themselves and the people they're helping. Similar to the Special Forces but with the priorities reversed.

I wonder if Peace Corps could be included here, or USAID.

Yes absolutely. I think bringing people from some military units and then the Peace Corps, USAID etc. together would be a way to get it happening quickly.

Interestingly -- perhaps you know this already -- the US military keeps a strict segregation between Peace Corps and the military: If you join one, you are forever-banned from joining the other. I'm not sure about the historical reasoning for it, though. Something else interesting: One of my childhood friends joined the Peace Corps, and wherever he went (in Africa), those countries always accused Peace Corps members of being CIA operatives. He was always super defensive about there being no CIA operatives in the Peace Corps, which in its own way was kind of suspicious.

Sorry for slow reply. That is very interesting, I never knew that but I guess it makes perfect sense. What I was/am thinking of is a group that is definitely military, but the goal is governance with the option of lethal force any time the need arises - with or without assistance from external units. If it existed I would have signed up years ago.