For most of his 18-year career as a U.S Navy pilot, Cmdr. David Fravor said his mother-in-law used to ask him a question: had he seen a UFO? For 15 years, the answer was no.

But one clear afternoon off the coast of California in 2004, he says, that changed.

Fravor, the commanding officer of a Navy squadron at the time, said he saw a flying object about the size of his plane that looked like a Tic-Tac after a break in a routine training mission. The object moved rapidly and unlike any other thing he had ever seen in the air. He has not forgotten it since.

Fravor’s story emerged this week after the Pentagon publicly acknowledged for the first time the existence of a recent program dedicated to studying unidentified flying objects. The funding for what was known as the Advanced Aviation Threat Identification Program ran from 2007 to 2012. But officials familiar with it said some of its efforts have continued.

And the news of its existence marks one of the significant disclosures about government research into flying objects — and the so-far-unproven possibility of extraterrestrial aircraft — since Project Blue Book, a lengthy Air Force study of thousands of UFOs was shut down in 1969. Project Blue Book failed to find “any technological developments or principles beyond the range of present-day scientific knowledge,” and no evidence of any “extraterrestrial vehicles,” according to the Air Force, though a small portion of the events it studied remain unexplained.

The encounter Fravor described was analyzed by the recent Defense Department program, he said, but its most significant questions – the nature of the object and what it was doing – have also remained unanswered.

Fravor says he is certain about one thing: “It was a real object, it exists and I saw it,” he said in a phone interview on Monday, as he described the sighting, on Nov. 14, 2004.

Asked what he believes it was, 13 years later, he was unequivocal.

“Something not from the Earth,” he said.

Fravor was the commanding officer of the A-41 Black Aces, a squadron of F/A-18 Hornet fighter planes doing an exercise some 60 to 100 miles off the coast between San Diego and Ensenada, Mexico, in advance of a deployment to the Persian Gulf for the Iraq War, he said.

An order came in for him to suspend the exercise and do some “real-world tasking,” about 60 miles west of their location, Fravor said. He said he was told by the command that there were some unidentified flying objects descending from 80,000 feet to 20,000 feet and disappearing; he said officials told him that they had been tracking a couple dozen of these objects for a few weeks.

When they arrived closer to the point, they saw the object, flying around a patch of whitewater in the ocean beneath.

“A White Tic-Tac, about the same size as a Hornet, 40-feet long with no wings,” Fravor described. “Just hanging close to the water.”

The object created no rotor wash – the visible air turbulence left by the blades of a helicopter – he said, and began to mirror the pilots as they pursued it, before it vanished.

“As I get closer, as my nose is starting to pull back up, it accelerates and it’s gone,” he said. “Faster than I’d ever seen anything in my life. We turn around, say let’s go see what’s in the water and there’s nothing. Just blue water.”

Fravor’s plane headed back to USS Nimitz aircraft carrier, but a separate crew that had taken off toward it began to search for it, tracking it for about a minute and a half and shooting a video, Fravor said.

But Navy superiors didn’t seem that interested in the event, so those like Fravor who had seen it, took a ribbing and X-Men jokes from their colleagues, and didn’t talk about it much after, Fravor said.

Fravor, who retired from the Navy in 2006 later shared the story with his wife and children, and some others who’d ask. But nothing really came of it until 2009 when a government official he declined to name contacted him while doing “an unofficial investigation.” Fravor declined to give more details about the official, but said he was later contacted by Luis Elizondo, an intelligence officer who ran the secretive program at the Department of Defense that was just disclosed.

Elizondo, who has since left the government to work for a private company that is hoping to promote UFO research for both scientific and entertainment purposes, is a large part of why the story about UFOs and the government’s program are in the news; he quietly arranged to secure the release of three videos of UFOs from the Pentagon, including the one shot the same day and place as Fravor’s.

Fravor, who has been talking about his experience to the To the Stars Academy of Arts and Sciences, the company where Elizondo is a consultant, said he knows that sharing his story has opened him up to ridicule – most but not all of it good-natured – but believes the incident should be more closely studied.

“I don’t think I was a nutjob as an officer in the Navy. I wasn’t drunk, I don’t do drugs. I got a good night’s rest, it was a clear day,” he said. “I think someone should have looked into it. Having talked to some of the other folks, it’s a big frustration that it’s coming out now and wasn’t discussed back in 2004.”

He believes that there could be some benefits from studying it.

“This is revolutionary technology to be able to accelerate, go up and down. Think about the advances that would bring to mankind,” he said. “What if it actually starts to get people to think outside the box.”

He said he’s been inundated with phone calls since his story was first told on Saturday. Still, the X-Men jokes continue.

“There is no mercy in my family or my friends,” he said.

The Washington Post’s Joby Warrick contributed to this report.

A U.S. Navy’s F/A-18 Super Hornet fighter approaches the deck of the Nimitz-class aircraft carrier USS Carl Vinson during the annual joint military exercise called Foal Eagle between South Korea and the United States at an unidentified location in the international waters, east of the Korean Peninsula, Tuesday, March 14, 2017. (AP Photo/Lee Jin-man)