As the Senate passed the bill that would have sold or banned TikTok, lawmakers heard directly from intelligence officials about the alleged national security threat posed by the app. Now two prominent senators the Office of the Director of National Intelligence to declassify and make public what they shared.

“We are deeply troubled by the information and concerns raised by the intelligence community in recent classified briefings to Congress,” wrote Democratic Senator Richard Blumenthal and Republican Senator Marcia Blackburn. “It is extremely important that the American people, especially TikTok users, understand the national security issues at stake.”

The exact nature of the intelligence community’s concerns about the app has long been a source of debate. Lawmakers in the House received a similar briefing just before the bill was voted on. But while the briefing appeared to bolster support for the measure, some members said they left unconvinced, with one lawmaker saying “nothing we’ve heard … is unique to TikTok.”

According to , some senators described their briefing as “shocking,” even though the group isn’t exactly known for a particularly nuanced understanding of the tech industry. (Blumenthal, for example, asked Facebook executives whether they would “commit to ending finsta.”) In his report, Axios says one lawmaker “said they were told that TikTok could spy on users’ devices’ microphones, track keystrokes and determine what users were doing in other apps.” That may sound alarming, but it’s also describing the types of social media services that have been in demand for more than a decade.

TikTok has argued that its relationship with parent company ByteDance would allow Chinese government officials to interfere with its service or spy on Americans. And so far, there is no public proof that TikTok has ever been used in this way. If US intelligence officials have evidence that is more than anecdotal, it would be a major bombshell in the long-running debate surrounding the app.