One of the three former US military officers, who testified Wednesday before a House Oversight Subcommittee, asserted the US was trying to cover up a project that “recovers and reverse-engineers unidentified flying objects (UFOs) or unidentified anomalous phenomena (UAP).

The hearing was called on as the lawmakers are urging the government to become more open about UFOs.

Ryan Graves, a former Navy pilot who runs Americans for Safe Aerospace, a group he founded to report UFO sightings, said: “If UAPs are foreign drones, it is an urgent national security problem. If it is something else, it is an issue for science. In either case, unidentified objects are a concern for flight safety.”

The objects spotted were regarded by the government as UAPs and it also released information in recent years, and some of them have not yet been explained.

However, authorities identified some of them as “balloon or balloon-entities,” as well as drones, birds, weather events or airborne debris like plastic bags.

Graves and David Fravor, a retired US Navy commander, both testified about their sightings of UFOs while they were in the military.

According to David Grusch, a former Air Force intelligence officer, the government covered up its research into the UFO sightings and stated that “he reported information to the intelligence community inspector general.”

“The technology that we faced was far superior than anything that we had,” Fravor said referring to a sighting he witnessed in 2004.

The latest hearing is an effort by legislators, intelligence officials and military personnel working on UFOs to investigate the matter on a national level.

“This is an issue of government transparency,” said Representative Tim Burchett, a Tennessee Republican who pushed to hold Wednesday’s hearing.

“We’re not bringing little green men or flying saucers into the hearing. … We’re just going to get to the facts. We’re going to uncover the cover-up, and I hope this is just the beginning of many more hearings.”

Sean Kirkpatrick, the director of the Pentagon’s All-domain Anomaly Resolution Office, — created by Congress to focus on UFOs — told a Senate subcommittee in April that the US government was tracking 650 potential cases of unidentified aerial phenomena, playing video from two of the episodes.

Kirkpatrick emphasised that there was no evidence of extraterrestrial life and that his office found “no credible evidence” of objects that defy the known laws of physics.

Department of Defense was also pressed by the lawmakers on the sightings, regarding them as national security threats.

“UAPs, whatever they be, may pose a serious threat to our military and our civilian aircraft, and that must be understood,” Democratic Rep. Robert Garcia of California said.

“We should encourage more reporting, not less on UAPs. The more we understand, the safer we will be.”

Jared Moskowitz, a Florida Democrat, said: “Many Americans are deeply interested in this issue, and it shouldn’t take the potential of nonhuman origin to bring us together.”

Grusch claimed that the US government not only has UAPs in its possession but also the remains of the allegedly “non-human” pilots of the aircraft. However, when he was pressed, he made it clear this was what he has been told by others, and he did not have firsthand information. “That’s something I’ve not witnessed myself,” he said.

Grusch told the panel he could provide a list of “cooperative and hostile witnesses” who could provide Congress with more information about the programs related to UAPs.

The witnesses, as well as several lawmakers, complained that information related to the unidentified sightings was overly classified by the US government.

“Right now we need a system where pilots can report without fear of losing their jobs,” Graves said. “There is a fear that the stigma related to this topic is going to lead to professional repercussions either through management or through their yearly physical check.”

Of the 650 cases the government is tracking, Kirkpatrick said, “We’ve prioritized about half of them to be of anomalous interesting value, and now we have to go through those and go ‘How much of those do I have actual data for?’”