You didn’t ask ~me~ the question, but if it means that much to you, the answer is just a click away. (You know how to read a profile page - yes?)
Since the referenced service was way before your time, here’s an explanatory link:
http://en.wikipedia.org/wiki/MACV
Oops! I almost forgot ... you haven’t answered my question ... regarding Posse Comitatus ... What will you do?
“regarding Posse Comitatus ... What will you do?”
He’ll roll over and play dead?
[just a hunch]