Justin Gaethje Training At FBI Headquarters Ahead of White House Fight

The UFC has infiltrated the FBI headquarters ... with fighters like Justin Gaethje using the agency's digs to prepare for Sunday night's Freedom 250 card at the White House.

The Highlight's setup was put on display in the promotion's new "Embedded" vlog that dropped on Wednesday ... when he casually said the FBI opened its doors to him ahead of his title fight with Ilia Topuria.

Gaethje said the makeshift gym has everything he needs to train -- mats and bags -- but it's gotta be extra cool rolling around on top of the FBI seal.

There's a bit of history between the two sides as well -- Gaethje was one of several MMA guys and gals invited to help train recruits at Quantico back in March.

Not only are fighters getting comfy with the special agents, they're also going to prepare for their bouts at the Eisenhower Executive Office Building, which is transforming into their locker rooms for the spectacle.

Topuria, on the other hand, hit up a nearby park for a late-night session recently ... proving the UFC really is everywhere in the nation's capital.