A former Pentagon official who led a recently revealed government programme to research potential unidentified flying objects (UFO) said that he believes there is evidence of alien life reaching Earth, the media reported.
"My personal belief is that there is very compelling evidence that we may not be alone," Luis Elizondo told CNN on Monday night.
News reports in The New York Times and Politico last week said the the Advanced Aviation Threat Identification Programme was begun largely at the behest of former Senate Majority Leader Harry Reid who helped shore up funding for it after speaking to a friend and political donor who owns an aerospace company and has said he believes in the existence of aliens.
Elizondo said that he resigned from the Department of Defence in October in protest over what he called excessive secrecy surrounding the programme and internal opposition to it after funding for the effort ended in 2012.
He said hat he could not speak on behalf of the government, but he strongly implied there was evidence that stopped him from ruling out the possibility that alien aircraft visited Earth.
"These aircraft are displaying characteristics that are not currently within the US inventory nor in any foreign inventory that we are aware of," Elizondo told CNN of objects they researched.
He said the programme sought to identify what had been seen, either through tools or witness reports, and then "ascertain and determine if that information is a potential threat to national security".
"We found a lot," he added.
"Things that don't have any obvious flight services, any obvious forms of propulsion, and manoeuvering in ways that include extreme manoeuverability beyond, I would submit, the healthy G-forces of a human or anything biological."
The New York Times' report on the government UFO study included a pair of videos of pilots remarking on something mysterious they were seeing.
One of the pilots, retired Commander David Fravor, told CNN that he had witnessed an object that looked like a "40-foot-long Tic Tac" manoeuvering rapidly and changing its direction during a flight in 2004.
Ryan Alexander of Taxpayers for Common Sense expressed dismay about the programme and cast it as a waste of money.
"It's definitely crazy to spend $22 million to research UFOs... Pilots are always going to see things that they can't identify, and we should probably look into them. But to identify them as UFOs, to target UFOs to research -- that is not the priority we have as a national security matter right now," Alexander told CNN.