From Project Sign to AARO: A Timeline of U.S. Government UFO Investigation

Official American interest in UFOs is older than the term "UFO." It has arrived in waves, each ending with the subject set aside, and each returning when footage or testimony made it impossible to keep aside.

Project Sign (1948)

In late 1947, after the surge of reports that followed Kenneth Arnold's sighting, the Air Force began collecting UFO reports under several short-lived efforts. These consolidated in early 1948 as Project Sign, run by the Air Technical Intelligence Center at Wright-Patterson Air Force Base. Sign collected and analyzed reports and produced at least one internal assessment that took the extraterrestrial hypothesis seriously; that assessment was not accepted at higher levels.

Project Grudge (1949)

Sign was succeeded in 1949 by Project Grudge, which took a markedly more skeptical posture. Grudge was short-lived and produced relatively little, and by its end the Air Force's active interest had effectively waned — though the reports had not.

Project Blue Book (1952–1969)

The revival came with the 1952 Washington, D.C. radar incidents, which made the subject impossible to set aside. In 1952 the Air Force reorganized the effort as Project Blue Book, led for much of its early life by Captain Edward Ruppelt, who is often credited with coining the term "UFO" to replace the suggestive "flying saucer." Blue Book collected more than twelve thousand reports over seventeen years and explained most of them; a small residue remained unidentified.

The Robertson Panel (1953)

In 1953 the Central Intelligence Agency convened a panel, chaired by physicist H. P. Robertson, to consider the national-security implications of UFO reports. The panel concluded the reports did not represent a direct threat but could, by clogging reporting channels, obscure genuine threats — and recommended a public campaign to debunk the subject.

The Condon Committee and closure (1966–1969)

Under continuing pressure, the Air Force commissioned the University of Colorado to study the subject. The resulting Condon Report, published in 1968, concluded that further study was unlikely to yield scientific value. Project Blue Book was closed in 1969, and for the next several decades the United States government had no formal public UFO program.

The long gap

From 1969 through the 2000s, official public interest was minimal. Behind the scenes, a small program — later reported as the Advanced Aerospace Threat Identification Program, funded beginning around 2007 — examined some incidents. It was not publicly acknowledged.

The public era (2017–present)

In December 2017, reporting in the New York Times disclosed that the Navy had recorded infrared footage of unidentified objects. The Department of Defense confirmed the authenticity of the Gimbal, Go Fast, and Tic Tac videos in 2020. Congress received an unclassified UAP report in 2021, held public hearings in 2022, and the All-domain Anomaly Resolution Office (AARO) was established the same year to investigate reports across all domains.

What the timeline shows

The pattern is clearer than any single entry: an event raises the subject; an investigation is opened; the investigation finds no conclusive answer; the subject is set aside; another event raises it again. The archive holds the institutional record alongside the sightings that prompted it, so that the two can be read together.

For the terminology that frames the modern end of this timeline, see What Does UAP Actually Mean?.