6004th Air Intelligence Service Squadron
The 6004th Air Intelligence Service Squadron was "the first covert (military intelligence) collection agency in the history of the United States Air Force". Begun by Major Donald Nichols as an impromptu extension of his pre-Korean War espionage in 1950, it was first dubbed "Special Activities Unit Number One".
Source: Wikipedia — 6004th Air Intelligence Service Squadron (CC BY-SA 4.0)