Finally after more than four years, the Defense Intelligence Agency (DIA) released more than 1,500 documents.
It includes government commissioned scientific reports and letters to the Pentagon regarding the UFO programme.
The haul includes reports into research on the biological effects of UFO sightings on humans, sets out categorisations for paranormal experiences, and studies into sci-fi-style tech.
The DIA, the Department of Defense's spy arm, said “some portions” of the documents “must be withheld in part” due to privacy and confidentiality concerns.
But the agency added the “DIA has not withheld any reasonably segregable non-exempt portions of the records”.
The bombshell Freedom of Information haul includes reports on the DIA's research into the biological effects of UFO sightings on humans.
And this includes burns, heart problems, sleep disturbances – and even bizarre occurrences such as “apparent abduction” and “unaccounted for pregnancy”.