A US intelligence report cannot give a definitive explanation of aerial phenomena spotted by military pilots but has found no evidence they are linked to aliens, according to two officials.
Multiple unexplained sightings from recent years have been examined in the report, due to go to the US Congress later this month.
Some cases include pilots heard exclaiming about objects flying in front of them and have been captured on video.
Events of this nature are regarded by the US military as safety issues given that, in many cases, the pilots who reported sightings were conducting combat training flights.
The two people briefed on the document said it found no proof of an extraterrestrial link and does not rule out the possibility the unidentified flying objects (UFOs) could be new technologies from other countries.
WATCH: Last year, the US Navy released previously classified footage from previous years of pilots spotting an unidentified object.
The US government is alert to the potential national security risk of an adversary flying novel technology over a military base or another sensitive site.
One of the officials said there is no indication that the unexplained phenomena are from secret US programmes.
Findings of the report were first published on Thursday by the New York Times.
A summary of the US government's knowledge of UFOs was required by Congress in December.
Work has since involved a US Department of Defense task force on unidentified aerial phenomena established last year.
An unclassified status report is expected to be available to the public this month – according to one of the two officials.
A Pentagon spokeswoman, Sue Gough, said the Pentagon's task force is "actively working with the Office of the Director of National Intelligence (DNI) on the report, and the DNI will provide the findings to Congress".
Cover image: US Department of Defense declassified UFO footage released by US Navy in 2020 (Picture NAVAIR).