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". In April or May 1951, it officially became the 6004th Air Intelligence Service Squadron. The 6004th was an unorthodox unit that engaged in espionage and aircrew escape and evasion, as well as collecting information. It was Far East Air Force's primary supplier of intelligence for the war, generating as many as 900 reports per month.

The origin of the 6004th Air Intelligence Service Squadron lies in the confusion following the start of the Korean War on 25 June 1950. When the North Koreans invaded South Korea, the United States Air Force had no military intelligence units. To fill the need for what he deemed "positive intelligence", Chief Warrant Officer (later Major) Donald Nichols improvised spy and espionage operations within the agent net he had formed prewar.

In July 1950, Nichols set up an impromptu parachute training course so espionage agents could be dropped behind the communist enemy's front lines. Some of them would shortly thereafter parachute behind North Korean lines to rescue the crew of a downed B-29 Superfortress. Forty-eight others would form the 13 spy teams dropped behind enemy lines during this time; they spotted and reported rear area targets for the Air Force.

Although the 6004th could draw upon air assets from the 581st Air Supply and Communications Wing or the Special Air Missions Detachment of the 21st Troop Carrier Squadron for infiltrating agents into North Korea's interior, exfiltration was by foot. This drawback would be addressed by beginning seaborne infiltrations via the 22nd Crash Rescue Boat Squadron, or scrounged fishing boats. Numerous islands lying just off the North Korean coast sheltered UN-backed guerrillas and offered sanctuary to seaborne infiltration missions, as well as refuge for downed UN pilots. The North Korean lines of communication running down either peninsular coast were tempting targets for sabotage. The North Koreans sometimes raided the islands, and were even known to wipe out guerrillas they found, but to no avail.

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