Washington — A small group of House lawmakers called Wednesday for greater transparency in the government's reporting on encounters with unidentified phenomena, in an unusual congressional hearing featuring the testimony of UFO witnesses.

But the hearing, which one freshman Democrat remarked was the most bipartisan discussion he'd seen in his seven months on Capitol Hill, oscillated between statements of concern about the potential national security threat posed by unknown objects flying close to U.S. military aircraft and more extreme allusions to government conspiracies to hide the existence of alien lifeforms.

Convened by a House Oversight subcommittee, the hours-long discussion captured the intensifying public interest in the unexplained and what federal authorities are doing to document and investigate such reports.

"We're not bringing little green men or flying saucers into the hearing - sorry to disappoint about half y'all," Rep. Tim Burchett, R-Tenn., said. "We're just going to get to the facts. We're going to uncover the coverup."

In response to reported encounters by Navy pilots, the U.S. military and the intelligence community have sought to more closely analyze such incidents. The sightings, including some that are believed to be drones or unmanned craft — like the Chinese surveillance airship shot down in U.S. airspace earlier this year — have fueled concerns that American adversaries could have developed new technologies that pose a threat to U.S. security.

The Pentagon has implemented new policies meant to encourage military personnel to come forward if they see something unusual so it can be investigated and accounted for, and last year established what it calls the All-domain Anomaly Resolution Office to further study such reports. NASA has undertaken a similar independent initiative.

Officials also have moved away from the term UFO, short for unidentified flying object, preferring instead "UAP," for unidentified anomalous phenomena — meant to be inclusive of unexplained objects also detected underwater or on land.

Lawmakers attending Wednesday's hearing said the government hadn't done enough.

"For decades, many Americans have been fascinated by objects mysterious and unexplained. And it's long past time that they got some answers," Rep. Jared Moskowitz, D-Fla., said in prepared remarks. "The American public has a right to learn about technologies of unknown origins, nonhuman intelligence and unexplainable phenomena," he added, noting that he was quoting Senate Majority Leader Charles E. Schumer, D-N.Y., and not "a UFO Twitter account."

"We must demand transparency from the Department of Defense, our Intelligence Community, and our defense industry on their UAP work," Rep. Glenn Grothman, R-Wis., the subcommittee's chairman, said Wednesday in his opening remarks.

So far, government officials say that none of the sightings has led to the discovery of extraterrestrial life. Earlier this year, the All-domain Anomaly Resolution Office determined that nearly 200 of 366 recently reported sightings were "unremarkable" and possibly can be attributed to routine objects found in the air, including drones, balloons and clutter, such as plastic bags.

Those quotidian explanations haven't stopped some from zeroing in on the 170 uncharacterized UAP incidents in that report that "require further analysis," and investigating the possibility that the U.S. government has collected evidence of alien visitations to earth and is withholding that information from the public.

"Do you have any personal knowledge of people who've been harmed or injured in efforts to cover up or conceal these extraterrestrial technology?" Burchett asked one witness, David Grusch, a former employee of the Pentagon's UAP task force, who has sparked controversy with his unsubstantiated claims that the government has a secret repository of downed alien spacecraft and corpses.

Grusch, a whistleblower who said he's suffered retaliation for going public with what he knows, couched many of his answers during the hearing by suggesting that saying what he knew could bring him harm. He told Burchett that he did "personally" know of people who were harmed or injured amid a coverup.

"Have you heard [of anyone being] murdered that you know of or have heard of?" Burchett asked.

"I directed people with that knowledge to the appropriate authorities," Grusch said.

Several congressional officials familiar with previous testimony that Grusch provided in classified hearings have said they were unable to substantiate or corroborate his claims that the U.S. government secretly runs a program to recover and reverse engineer crashed alien vessels.

Wednesday's hearing was not the first in Congress on UAPs. But it was unusual in that it focused on eyewitnesses to the phenomena and others who have closely studied them. Previous hearings have featured testimony from more senior government officials who have not claimed to have had firsthand experience with UAPs.

The two other witnesses, Ryan Graves, who heads Americans for Safe Aerospace, and David Fravor, a retired Navy commander, both said they witnessed UAPs during their service as Naval pilots based in Virginia and California, respectively, and spoke to the stigma of reporting the incidents. They urged greater research and transparency for the sake of national security and the safety of those operating military and commercial aircraft.

"If UAP 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 concern for flight safety," Graves told the committee. He said his organization had received testimony from more than 30 UAP eyewitnesses, most of them commercial airline pilots.