Unidentified UNSC military base
From Halopedia, the Halo wiki
This UNSC military base is a military installation located on the planet Sargasso. During the Battle of Sargasso in 2546, Gunnery Sergeant Edward Buck and his ODST fireteam, Alpha-Nine, arrived here after recovering vital data from a Lethbridge Industrial laboratory in the nearby town of Belisk. They were debriefed in the base's conference room by Captain Veronica Dare of ONI; Dare personally reprimanded Buck for disobeying orders during the battle and threatened him with a charge of insubordination.