This timeline covers institutional developments only: government programs, official reports, congressional hearings, legislative action and formal scientific engagement. Individual sightings and unverified accounts are outside its scope.

1947–1969 — The investigation era

1947

Project Sign established — first official U.S. government UAP investigation

The U.S. Air Force created Project Sign following a wave of aerial anomaly reports. Sign's final classified report concluded some objects might be of extraterrestrial origin — a finding suppressed by Air Force leadership and not publicly acknowledged at the time.

USAF
1949

Project Grudge replaces Project Sign

Grudge's institutional mandate shifted toward debunking rather than investigation. Its final report attributed all cases to misidentification, hoax or psychological causes — a conclusion later criticised for methodological inadequacy.

USAF
1952

Project Blue Book established — longest official investigation

The Air Force's most extensive UAP study program, running until 1969. Investigated 12,618 reports. 701 remained officially unexplained at closure. The project's methodological limitations were later documented by independent researchers and government reviews.

USAF
1953

Robertson Panel — CIA convenes scientific review

The CIA assembled the Robertson Panel to evaluate UAP evidence. The panel recommended a public debunking campaign and surveillance of civilian UAP research groups — documented recommendations that shaped Air Force policy for the following decade.

CIA
1969

Project Blue Book closed

Following the Condon Report (University of Colorado study), the Air Force terminated Blue Book and concluded no UAP constituted a national security threat. The program's methodological limitations were later acknowledged in subsequent government reviews, including AARO's 2024 Historical Record Report.

USAF

1977–2006 — International programs and the gap years

1977

GEIPAN established — France creates permanent UAP investigation body

France's space agency CNES created GEIPAN (Groupe d'Études et d'Informations sur les Phénomènes Aérospatiaux Non-identifiés), a formal government UAP investigation unit operating continuously since 1977. GEIPAN publishes its case database publicly and remains the longest-running government UAP program.

France / CNESSource →
2004

USS Nimitz incident — the Tic-Tac encounter

U.S. Navy pilots from the USS Nimitz Carrier Strike Group encountered an unidentified object during training exercises off the California coast. The encounter was recorded on infrared sensors. Pilot David Fravor and others filed formal reports. The footage became one of three videos later officially authenticated by the Pentagon in 2020.

U.S. Navy

2007–2019 — AATIP and the return of official investigation

2007

AATIP established — Advanced Aerospace Threat Identification Program

A classified Pentagon program to investigate UAP, reportedly funded at $22 million over five years and run by Luis Elizondo within the Defense Intelligence Agency. The program's existence was not publicly known until investigative reporting in 2017.

DoD / DIA
2017

AATIP existence confirmed — Pentagon acknowledges program

Investigative reporting by the New York Times revealed AATIP's existence, including footage of the 2004 Nimitz encounter. The Pentagon confirmed the program had existed. Luis Elizondo subsequently resigned and began advocating publicly for further disclosure.

DoD — confirmed
2019

U.S. Navy formally acknowledges three UAP videos as authentic

The Navy confirmed that FLIR1 (2004), GIMBAL (2015) and GOFAST (2015) depicted real observations by Navy pilots of unidentified aerial phenomena. First formal military authentication of UAP footage.

U.S. Navy

2020–2022 — Formal disclosure begins

2020

Pentagon officially releases and authenticates three UAP videos

The Department of Defense released FLIR1, GIMBAL and GOFAST via official statement, confirming them as genuine footage captured by military aircraft. First official DoD release of UAP footage with explicit authentication.

2021

ODNI Preliminary Assessment — 144 cases reviewed, 143 unexplained

The Office of the Director of National Intelligence published its unclassified UAP assessment covering 144 incidents from 2004–2021. One was attributed to a deflating balloon; 143 lacked sufficient data for explanation. The report formally acknowledged UAP as a national security and aviation safety concern.

2022

AARO established — permanent DoD UAP investigation office

The Pentagon replaced the UAP Task Force with the All-domain Anomaly Resolution Office, a permanent body with expanded authority across air, space, maritime and subsurface domains. AARO was mandated to coordinate across all military branches and intelligence agencies.

2023–2024 — Congress, science and the historical record

2023

House Oversight Committee hearing — Grusch, Graves and Fravor testify under oath

The most prominent public UAP congressional hearing in history. Former intelligence officer David Grusch testified under oath about alleged government possession of retrieved non-human craft. Navy pilots Ryan Graves and David Fravor corroborated encounter reports. Full transcript in the congressional record.

2023

NASA publishes independent UAP study — formalises research function

A 16-member independent team recommended scientific data collection frameworks, called for reduced reporting stigma, and formalised UAP as a legitimate research area. NASA subsequently established a permanent UAP research function within its Science Mission Directorate.

2024

AARO Historical Record Report — Volume I published

The first authorized government historical analysis of UAP programs, submitted to Congress as a public document. Reviewed U.S. government UAP-related activities from 1945 onward. Found no verifiable evidence of non-human origin but acknowledged significant classification and information-sharing failures within the institutional record.

DoD / AAROReport →
2024

AARO publishes public UAP imagery archive

The Department of Defense launched a public repository of declassified UAP footage from military sensors, with explicit confidence assessments for each case. Archive updated through January 2026.

DoD / AAROArchive →

2025–2026 — The disclosure directive era

Sep 2025

House Oversight Task Force hearing — military witnesses on UAP transparency

Military veterans including Dylan Borland testified before Congress on UAP encounters and institutional responses. Lawmakers pressed for stricter oversight and legal protection for personnel reporting UAP observations.

Congress
Dec 2025

FY2026 NDAA signed with three UAP-specific provisions

The annual defense legislation mandated expanded congressional briefings on UAP intercepts since 2004, a classification matrix for affected programs, and streamlined inter-agency data sharing. Described by the Disclosure Foundation as incremental but meaningful progress.

LegislationSource →
Feb 2026

Trump directs Pentagon to release UAP files — AARO caseload exceeds 2,000

President Trump announced he was directing federal agencies to prepare UAP file releases, citing "tremendous interest." Defense Secretary Hegseth confirmed compliance efforts had begun. AARO's active caseload was disclosed as exceeding 2,000 cases, up from 1,600 in late 2024.

White House / DoDSource →
Mar 2026

White House registers alien.gov and aliens.gov — no content published

Two new government domains registered approximately one month after Trump's disclosure directive. The sites carried no content at registration. A Pentagon spokesperson deferred questions to the White House, whose only public response was "Stay tuned." Former Deputy Assistant Secretary of Defense Christopher Mellon described the underlying declassification process as likely to take considerable time.

White HouseSource →
Apr 2026

H.R. 8197 introduced — legislation to terminate AARO

Congressman Tim Burchett introduced a bill on April 6 to shut down AARO within 60 days and legally prohibit any replacement centralized office. The bill followed Congresswoman Anna Paulina Luna's public call to defund the office, citing inadequate disclosure and unsatisfactory responses to the House Task Force. Now before the House Committee on Armed Services. No vote scheduled.