TikTok, the viral video-sharing app owned by China’s ByteDance Ltd., said certain employees outside the U.S. can access information from American users, stoking further criticism from lawmakers who have raised alarms about the social network’s data-sharing practices.

The company’s admission came in a letter to nine U.S. senators who accused TikTok and its parent of monitoring U.S. citizens and demanded answers on what’s becoming a familiar line of questioning for the company: Do China-based employees have access to U.S. users’ data? What role do those employees play in shaping TikTok’s algorithm? Is any of that information shared with the Chinese government?

Currently, China-based employees who clear a number of internal security protocols can access certain information on TikTok’s U.S. users, including public videos and comments, TikTok Chief Executive Officer Shou Zi Chew said in the June 30 letter obtained by Bloomberg News. None of that information is shared with the Chinese government, and it is subject to “robust cybersecurity controls,” he said.

The social network said it’s working with the U.S. government on strengthening data security around that information — particularly anything defined as “protected” by the Committee on Foreign Investment in the U.S., or CFIUS. This new effort, called “Project Texas,” includes physically storing U.S. information in data centers on U.S. servers owned by software giant Oracle Corp. TikTok is also shifting its platform to Oracle’s cloud infrastructure, which means the app and the algorithm will be accessed and deployed for U.S. users from domestic data centers.

“TikTok’s response confirms our fears about the CCP’s influence in the company were well-founded,” Republican Senator Marsha Blackburn of Tennessee told Bloomberg on Friday. “The Chinese-run company should have come clean from the start, but it attempted to shroud its work in secrecy. Americans need to know if they are on TikTok, Communist China has their information.”

Several senators, all Republicans, in a June 27 letter cited a report in BuzzFeed News that said TikTok’s US consumer data was accessed by company engineers in China. The lawmakers said in the letter that TikTok and its parent “are using their access to a treasure trove of U.S. consumer data to surveil Americans.” The New York Times reported earlier on TikTok’s response.