Nathan Farragut Twining (1897–1982) was an American airman who rose from National Guard sergeant to chief of staff of the US Air Force from 1953 to 1957 and chairman of the Joint Chiefs of Staff from 1957 to 1960, the first Air Force officer to hold that post. In UFO history he is the general who signed a September 23, 1947 letter, written while he commanded the Army Air Forces' Air Materiel Command, stating that "the phenomenon reported is something real and not visionary or fictitious."

Born in Monroe, Wisconsin, Twining served in the Oregon National Guard before entering West Point in 1917 on a wartime-shortened course and graduating in 1919. He moved from the infantry to the Air Service in 1922 and flew fighters between the wars. In World War II he took command of the Thirteenth Air Force in the South Pacific in January 1943, then led the Fifteenth Air Force from Italy and briefly commanded the B-29s of the Twentieth Air Force before Japan surrendered. He then took over Air Materiel Command at Wright Field, Ohio.

The Twining memo grew out of the summer 1947 wave of flying-disc reports. Army Air Forces intelligence had asked his command for its view, and his intelligence director, Colonel Howard McCoy, convened the command's engineers to study the reports. Twining's reply judged that the objects were probably disc-shaped and about as large as man-made aircraft, that some incidents might be natural phenomena such as meteors, and that reported maneuvers raised the possibility that some were "controlled either manually, automatically or remotely." It also allowed that they might come from a secret American project or a foreign nation with new propulsion, and it cited "the lack of physical evidence in the shape of crash recovered exhibits." He recommended a priority, a security classification and a code name for a detailed study, and by late December headquarters had established Project Sign at Wright Field.

Twining left the command in 1947 to lead Alaskan Air Command, became vice chief of staff in 1950 and chief in 1953, overseeing the arrival of the B-52 and early missiles. Eisenhower named him Joint Chiefs chairman in 1957; he retired in September 1960. His name also runs through the Majestic-12 papers of the 1980s, which list him among the alleged committee's "designated members," and the Cutler–Twining memo, a 1954 note addressed to him that researchers found in the National Archives in 1985. The Archives has listed problems with that memo, including a classification marking not used until decades later and evidence that its supposed author, Robert Cutler, was abroad that day, and the FBI judged an MJ-12 document it examined "completely bogus."

The genuine 1947 letter drew fresh attention in May 2026, when social-media posts presented it as newly released by the government, although the Condon report had printed it in full in 1969. A June 2026 government records release included a 1971 Australian assessment by scientist Harry Turner that retraced the Air Force projects from Sign to Blue Book. Twining helped build the jet and missile Air Force of the 1950s, but his most quoted words remain the 1947 judgment that the discs were real enough to justify a classified study, which began two decades of official Air Force UFO investigation.