From Combine OverWiki, the English Half-Life Wikia
A Member of the Military Police.
Military Police are members of the United States Armed Forces who guard the
Hazardous Environment Combat Unit's training base. They are charged with guarding areas that need security clearance to enter, and taking and storing the weapons that a member of the HECU uses during his training exercises. Each soldier is armed with a
Heckler & Koch MP5N and appear to wear
Powered Combat Vests. It is unknown what connection they have, if any, to the
Black Ops.
They are known to be connected to the G-Man, however: As Adrian Shephard advances past a large military structure on his way to meet Drill Instructor Sharpe, the G-Man and a Military Policeman can be seen watching him.
[edit] Trivia
Firing on any member of the Military Police will end the game.
