United States Air Force

The United States Air Force is the aerial warfare service branch of the US Armed Forces. Historically, it was the primary military branch tasked with investigating UFOs through public and classified programs like Project Sign, Project Grudge, and Project Blue Book. The USAF has historically shaped the public narrative on UFOs, often attributing sightings to misidentifications or natural phenomena before closing its official investigations in 1969.

The historical lead agency for US government UFO investigations (e.g., Project Blue Book) and a primary source of military UAP encounters.