The US Navy has only recently introduced a formal procedure for reporting sightings of unidentified flying objects, bowing to the constantly growing number of UFOs being spotted by servicemen. Previously, the Navy preferred to simply ignore such reports.

Luis Elizondo, former head of the Pentagon's Advanced Aerospace Threat Identification Program (AATIP), a department devoted to studying UFO sightings, has revealed in an interview with Live Science that although the majority of reports could be given rational explanations, some of them were unexplainable from the standpoint of modern technology and science.

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He brought up the example of UFOs reported to the AATIP traveling at speeds over five Mach and making sudden changes in course without losing velocity. Elizondo explained that such manoeuvres would generate 400 to 500 G-forces, while modern aircraft can withstand a maximum of around 16 to 18 Gs and pilots up to 9 Gs, and even then only for short periods of time.

"They don't have engines or even wings, and they are able to seemingly defy the natural effects of Earth's gravitational pull", he said.

The former AATIP chief noted, however, that despite multiple UFO reports proven to be at least plausible, he hesitates to call them extra-terrestrials, as his department had not found enough evidence to suggest that they originated from other planets. Elizondo believes there is a chance that a country here on Earth has managed to develop such aircraft, which, if true, would be "strategic game-changers".

The Pentagon expressed little enthusiasm for the AATIP and didn't take fears that a foreign government could be behind the creation of revolutionary aircraft seriously. Elizondo indicated that this attitude was partially behind his decision to leave the department for good.

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Some things have apparently changed since his resignation in 2017, as the US Navy in 2019 initiated a formalised channel to report UFO sightings by its servicemen. This change reportedly came in response to a growing number of the cases where pilots or radar crew detect objects moving in strange or unnatural ways.