Department of Energy and intelligence community officials briefed members of the Senate Energy and Natural Resources Committee on classified information related to COVID-19’s origins Thursday but offered no definitive revelations, according to lawmakers.

The briefing follows the news that the department now concludes with “low confidence” that the virus more likely originated in a lab in Wuhan, China, rather than through natural evolution. The Federal Bureau of Investigation also believes the “lab leak” theory with “moderate confidence,” although the National Intelligence Council and four other agencies hold the opposite view. 

The officials offered details on why they changed from their previously neutral position, according to senators in the briefing. The DOE’s national labs employ scientists in a range of specialties beyond energy.

“They were very, very generous and explicit as far as what they know, how they know, when they knew — things of this sort,” said Chairman Joe Manchin III, D-W.Va. “But no one’s exactly 1,000 percent.”

Sen. Josh Hawley, R-Mo., who also attended the briefing, sponsored a bill to declassify relevant intelligence that passed the Senate by unanimous consent on March 1 and passed the House 419-0 on March 10. That bill still awaits President Joe Biden’s signature, but the White House has not indicated whether Biden will sign.

“Hopefully that will all soon be declassified,” Hawley said of the Energy Department’s assessment. “But it’s not like shattering. I mean, it’s nothing that the FBI and others hadn’t really already weighed.”

Manchin said he questioned the officials on the country’s preparedness for future pandemics during the briefing, and that officials are working to improve security measures.

“They’re moving in that direction,” he said. “They’re very much aware of it.”

Hawley said he hopes declassifying intelligence will lead to new information, with more members of the public scrutinizing the information and connecting new dots.

“It’s no secret that China’s been hugely obstructive. Hugely obstructive,” he said. “And, you know, that’s going to continue but that doesn’t mean that we can sit back and say we’ll never know. And indeed, we have multiple agencies now that think they do know.”