UNSC High Command, often abbreviated as HIGHCOM, is the highest operational command of the United Nations Space Command and is ultimately in charge of all personnel, equipment, and facilities used by the UNSCDF. It was sometimes erroneously referred to as "the Admiralty", which was a misnomer as its staff was composed of personnel from all branches, not just the Navy.
It was split into two commands: the Unified Ground Command, coordinating all UNSC ground forces, and the UNSC Naval Command, in charge of the Navy. It exercises local authority through regional CENTCOMs, which have responsibility over certain areas of space.
Top-level brass from every branch form the UNSC Security Committee of HIGHCOM. With headquarters at the planets Reach and Earth, HIGHCOM is the equivalent to the modern Pentagon of the United States military. HIGHCOM has directed the strategy for the actions of the UNSC since its very beginning. From combating rebel forces, such as the Eridanus Rebels, to the genocidal war waged by the Covenant, HIGHCOM has been the source of all strategy and information about war. After the fall of Reach, the headquarters was relocated to the High Com Facility Bravo-6 in Sydney.