(CNN) Retired US Navy pilot David Fravor trusts what he saw with his own two eyes. And what he saw, in 2004, was a flying object that cannot be identified. Otherwise known as a UFO.

It was a "white object, oblong, pointing north, moving erratically," he told CNN's Jim Sciutto on Tuesday evening.

At the time of the sighting, Fravor was a naval commander, in the cockpit of a US aircraft, and the details of the encounter are still fresh in his mind.

"As I got close to it ... it rapidly accelerated to the south, and disappeared in less than two seconds," he said.

The object in question had no wings. As such, one might think it was a helicopter. Not so, said Fravor, who noted clear differences between a chopper and the aircraft he came across.

"When helicopters move side to side, they kinda slow, and then they pick up speed going the other way," Fravor explained. "This was extremely abrupt, like a ping pong ball, bouncing off a wall. It would hit and go the other way."

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The movements of the flying object were unlike anything Fravor had ever seen, largely due to its agility and the way it handled.

Speaking live with Sciutto, the former naval pilot said the aircraft had "the ability to hover over the water, and then start a vertical climb, from basically zero up towards about 12,000 feet, and then accelerate in less than two seconds, and disappear."

As a believer in UFO's, Fravor knows there are skeptics.

"It's easy to doubt what we can't explain," he said. However, he reminded viewers that he was among other aviation experts, all of whom did their due diligence on that day.

"It was an actual object that we tracked ... for somewhere around five minutes, before it rapidly accelerated."

"It's easy to doubt what we can't explain" - Commander David Fravor, a former U.S. Navy pilot, encountered an unknown flying object, calling it "something I had never seen in my life" https://t.co/SiPTYb2xM1 pic.twitter.com/mpaiudlnVL — OutFrontCNN (@OutFrontCNN) December 20, 2017

NY Times: Pentagon study of UFOs revealed

Fravor's account comes as the New York Times reported the Pentagon has researched the possible existence of UFOs

According to a report in the paper Saturday, the once completely classified project that began because of the intense interest in the subject by former Sen. Harry Reid of Nevada.

The Advanced Aviation Threat Identification Program was launched in 2007 after the Nevada Democrat spoke to his longtime friend, Robert Bigelow, the billionaire founder of an aerospace company.

Bigelow has spoken about his belief in UFOs visiting the United States as well as the existence of aliens.

Among the anomalies the program studied, the paper said, were video and audio recordings of aerial encounters by military pilots and unknown objects, as well as interviews with people who said they had experienced physical encounters with such objects.

The Pentagon says the program has since been shuttered.

Former Pentagon UFO official: 'We may not be alone'

A former Pentagon official who led a recently revealed government program to research potential UFOs added Monday evening that he believes there is evidence of alien life reaching Earth.

"My personal belief is that there is very compelling evidence that we may not be alone," Luis Elizondo said in an interview on CNN's "Erin Burnett OutFront."

Elizondo told the New York Times he resigned from the Department of Defense in October in protest over what he called excessive secrecy surrounding the program and internal opposition to it after funding for the effort ended in 2012.

Elizondo said Monday that 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 -- 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," Elizondo said of objects they researched.

He said the program sought to identify what had been seen, either through tools or eyewitness reports, and then "ascertain and determine if that information is a potential threat to national security."

"We found a lot," Elizondo said. The former Pentagon official said they identified "anomalous" aircraft that were "seemingly defying the laws of aerodynamics.

"Things that don't have any obvious flight services, any obvious forms of propulsion, and maneuvering in ways that include extreme maneuverability beyond, I would submit, the healthy G-forces of a human or anything biological."