A Navy official also said at Tuesday's hearing that investigators are "reasonably confident" the floating pyramid-shaped objects captured on one leaked, widely seen military video were likely drones.
That footage, which the military confirmed last year was authentic, had helped spur interest in purported UFOs, also referred to as "unidentified aerial phenomena" or UAPs.
Indiana Rep. André Carson, the Democratic chairman of the House Intelligence Counterterrorism, Counterintelligence, and Counterproliferation Subcommittee, called Tuesday's hearing, the first in more than 50 years focused on the aerial incidents.
UAPs, Carson said, "are a potential national security threat and they need to be treated that way."
"For too long the stigma associated with UAPs has gotten in the way of good intelligence analysis," he added. "Pilots avoided reporting or were laughed at when they did."
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The number of UAP reports has risen to "approximately 400," a significant increase from the 144 between 2004 and 2021 that were tracked in last year's report, according to Scott Bray, the deputy director of Naval Intelligence. Bray told the House panel that the spike was due to a reduction in the stigma associated with stepping forward to report such incidents in the wake of the 2021 report.
"We've seen an increasing number of unauthorized and or unidentified aircraft or objects and military control training areas and training ranges and other designated airspace," Bray said. "Reports of sightings are frequent and continuous."
But Bray believes many of the newly disclosed accounts are actually "historic reports that are narrative-based" from prior incidents that people are only now coming forward with, which leads him to believe there will be fewer new accounts in the future.
Last year's intelligence report could only explain one of the documented 144 encounters and did not contain the words "alien" or "extraterrestrial." The report stated then that the UAP incidents would require further study.
At Tuesday's hearing, Bray echoed last year's conclusion that most of the phenomena were likely physical objects and noted that "the UAP task force doesn't have any wreckage that ... isn't consistent with being a terrestrial origin."
Even so, Bray said, questions remain.
"I can't point to something that definitively was not man-made, but I can point to a number of examples which remain unresolved," Bray said, citing video of a 2004 incident in which a Navy pilot recorded an unusual, Tic Tac-like object over the water.
"We want to know what's out there as much as you want to know what's out there," said Ronald Moultrie, the Pentagon's top intelligence official, who also testified at the hearing.
Moultrie said the Pentagon is establishing an office to speed up "the identification of previously unknown or unidentified airborne objects in a methodical, logical and standardized manner."
"We also understand that there has been a cultural stigma surrounding UAP," Moultrie said. "Our goal is to eliminate the stigma by fully incorporating our operators and mission personnel into a standardized data gathering process."
"Our goal is to strike that delicate balance: one that enables us to maintain the public's trust while preserving those capabilities that are vital to the support of our service personnel," he said.
Bray said "Navy and Air Force crews now have step-by-step procedures for reporting on a UAP on their kneeboard in the cockpit" and that these efforts have led to more reporting.
The increasingly mainstream interest in UFOs and UAPs has been sparked in recent years by leaks of once-classified videos and the Navy's release of footage from their pilots' own encounters.
At Tuesday's hearing, the defense officials played three clips to help explain how brief the aerial incidents could be, making it very difficult to determine what was seen in the videos.
In one of the more notable cases, the officials detailed how "considerable effort" went into determining a theory for what was observed.
Bray played footage taken in July 2019 off the California coast from the deck of the destroyer USS Russell that seemed to show several pyramid-shaped objects hovering above the ship.
Bray acknowledged that investigators did not initially have an explanation for what was seen in the green night scope video -- until they were able to contrast it with a more recent video of an incident that occurred off the coast of the Atlantic Ocean.
Officials who looked at that video found a similar pyramid shape. They concluded the phenomena were likely from drones that had been seen on sensors from another Navy asset.
"We're now reasonably confident that these triangles correlate to unmanned aerial systems in the area," Bray explained. "The triangular appearance is a result of light passing through the night vision goggles and then being recorded by an SLR camera."
"This is a great example of how it takes considerable effort to understand what we're seeing in the examples that we are able to collect," he added.
Ahead of the hearing, Jeremy Corbell, a documentary filmmaker and UFO enthusiast who made public that "pyramid" video last year, said he was happy to see increasing awareness and government action.
"What is so great is that this is a direct response to public will," Corbell told ABC News. "It is direct response to public pressure. It is representative government representing the citizens and their interest."
"I am encouraged by the public desire to know and find out the truth of what UFOs represent to humankind," Corbell said then. "It's the biggest story of our time. And finally we're beginning to have the conversation without ridicule and stigma that has so injured the search for scientific truth on this topic."
Moultrie, the Pentagon official, said at Tuesday's hearing that he wasn't immune to a bit of the zeal himself as a science fiction fan.
"I have gone to conventions -- I'll say it on the record. Got to break the ice somehow," he told the panel in one lighthearted line of questioning, adding, "We have our we have our inquisitiveness. We have our questions."
ABC News' Matthew Seyler contributed to this report.