A former Pentagon employee, tasked with finding evidence of unidentified flying objects, has expressed his belief that humans are not alone in the universe.
CNN reports Luis Elizondo was part of the Advanced Aviation Threat Identification Program, which hoped to identify objects of mysterious origin, and decide whether the object or information posed a threat to national security.
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It was established by former Senate Majority Leader Harry Reid, after he secured funding from an anonymous donor, who believed in the existence of aliens.
During his time in the programme, Mr Elizondo says they found many aircraft that seemed to defy the laws of physics and possibly came from outer space.
"These aircraft - we'll call them aircraft - are displaying characteristics that are not currently within the US inventory, nor in any foreign inventory that we are aware of," Mr Elizondo told CNN.
"Things that don't have any obvious flight services, any obvious forms of propulsion and manoeuvring in ways that include extreme manoeuvrability beyond, I would submit, the healthy G-forces of a human or anything biological."
Mr Elizondo left the Department of Defense in October, protesting what he called excessive secrecy over the programme and difficulties securing funding, after the original funding ended in 2012.
Leaving the programme has not changed his views about UFOs, though, and he remains committed to the idea that humans may not be alone in the universe.
"My personal belief is that there is very compelling evidence that we may not be alone," he told CNN.