UNSC Fleet Command
From Halopedia, the Halo wiki
UNSC Fleet Command, or as it is more colloquially known, FLEETCOM, is the commanding body of the UNSC Navy. All naval vessels report through FLEETCOM, and the commanding Admirals of the UNSC.
FLEETCOM has two known headquarters, one on the planet Reach at an undisclosed location, but most likely nearby Mechanite Mountain and ONI's CASTLE Base. The second known headquarters is in Sydney, Australia, on the planet Earth.
