The USCM Bunker is a restored vanilla surface dungeon. It was cut in Cheerful Giraffe due to the game's lore restructuring, but has been resurrected for FU use.
The FU incarnation of this bunker is not much different than its beta incarnation: it is still occupied by human USCM soldiers, Cleaning Bots, Repair Bots, and Serpent Droids. The only real difference is that the FU Version of the USCM occupants use Frackin weapons (usually gauss rifles, laser rifles, XT-3 Laser cannons, etc.)
It does not feature tile protection.