There are more than 1,500 pages of UFO-related information in the collection of records, which comes from the Advanced Aerospace Threat Identification Program (AATIP), a clandestine United States Department of Defense program that operated from 2007 to 2012.

The information was never classified as secret or top secret per say, but became more widely known about in 2017 after former program director Luis Elizondo resigned from the Pentagon and revealed to the world multiple now-infamous films of an unidentified aircraft moving in apparently inconceivable ways.

Soon after it was disclosed that the AATIP was in existence, the American edition of the British tabloid The Sun filed a Freedom of Information Act inquiry for any and all records pertaining to the program. 

Four years later, on April 5, 2022, the United States Defense Intelligence Agency (DIA) complied with the request by providing The Sun with an additional 1,574 pages of information.

Reports on UFO encounters and human biology are among the papers found in the trove, according to The Sun. Studies on advanced technology like invisibility cloaks are also among the records along with plans for deep space exploration and colonization. The AATIP informed The Sun that certain papers were "withheld in part" to protect privacy.