(NewsNation) — UFO whistleblower David Grusch is vowing to press on with his campaign to get more secrets out to the public about unidentified aerial phenomena.

In an interview with NewsNation’s Elizabeth Vargas, Grusch said he plans to discuss what he knows “firsthand” in an upcoming op-ed.

“I will be discussing what I actually do know firsthand. I just could not overtly discuss that at the time, including at the (congressional) hearing because the Pentagon and the IC were sitting on some of my prepublication paperwork at the time,” Grusch told Vargas.

NewsNation correspondent Ross Coulthart was the first to interview Grusch and brought the world the former Air Force intelligence officer’s claims the U.S. government is covering up a UFO, or unidentified flying object, retrieval program.

Coulthart said he has a “pretty good idea” what information Grusch may release in the coming weeks.

“I’m actually very excited that you’ve managed to pull that out of him,” Coulthart told Vargas. “Because I’ve been waiting for a while for him to provide a rejoinder to the critics who have constantly asserted there is no firsthand evidence.”

While Coulthart said he can’t speak with any specificity on the contents of Grusch’s possible op-ed, he thinks he may have an idea of what it could feature.

“I suspect it’s something to do with either photographic or video material that he may have seen, but I’m only speculating,” Coulthart said.

Coulthart maintains more people will likely come forward with their own UFO claims after Grusch presented his information.