WASHINGTON (NEXSTAR) – On Capitol Hill, lawmakers held a hearing on unidentified flying objects, during which defense officials said they have some 400 reports from military personnel of UFOs, and while they can explain some, they can’t explain others.

In the first hearing of its kind in 50 years, defense officials confirmed sightings of unidentified flying objects, or as the military calls them “UAPs”.

However, Deputy Director of Naval Intelligence, Scott Bray, explained “we have detected no emanations within the UAP task force that would suggest it’s anything non-terrestrial.”

Officials said there have been no collisions between U.S. aircraft and the objects, but there have been 11 near misses.

During the hearing, Representative Raja Krishnamoorthi (D-IL) asked “have we attempted to communicate with those objects?”

To which Bray said there have been no attempts.

Some of the objects were later classified as drones, but defense officials said there are sightings they still cannot explain.

The defense department says it is taking the reports seriously and continues to expand its office that’s gathering and analyzing reports of UFOs.

Representative Rick Crawford said “it’s not about finding alien spacecraft, but about delivering dominant intelligence.”

Some lawmakers said the sightings could be evidence of secret U.S. or foreign technology.

But California congressman Adam Schiff (D-CA) was unsure.

“There is something there, measurable by multiple instruments and yet it seems to move in directions that are inconsistent with what we know of physics or science,” Schiff said.

After the public hearing, a classified version of the hearing on UFOs continued behind closed doors.

The military is encouraging service members to report sightings and some branches have already established procedures for reporting and tracking UFO data.