You are right, DA. I was up really late when I posted that ... not sure how I confused Marines with Militia. It was the USCMC, though they simply used USCM and dropped the "Corps" part of the acronym. You can see evidence of this by looking at the picture used for our very own Cpl. John Morden aka "Reaper." On his arm is tattooed USCM along with some numbers I can  hardly make out. I know in the movie 'Aliens' Sgt. Apone refers to them simply as "the Marine Corps" and "the Corps."