Immigration officers have interrogated more than 30 TikTok employees who traveled to the US, Forbes reports. Some workers at TikTok and its China-based parent company, ByteDance, have been pulled aside by Customs and Border Protection (CBP) and held for additional questioning, according to the report. Many of the workers who have been singled out are Chinese nationals.

Some of the people who have been interrogated work in machine learning or data engineering. CBP agents have asked them about their access to US users’ TikTok data. The workers have also been asked about the location of TikTok’s US-based data centers and their own individual involvement with Project Texas, a massive corporate restructuring project designed to wall off US user data from ByteDance’s workers in China. 

CBP’s questioning has also veered into more personal territory. According to Forbes, TikTok employees have been asked whether they are members of the Chinese Communist Party and have also been asked to provide information about their schooling and political connections in China. A source told Forbes that CBP agents have a “dedicated, printed list of questions” they use to interrogate TikTok and ByteDance workers. 

TikTok CEO Shou Chew has been subjected to similar questioning. During a congressional hearing in January, Sen. Tom Cotton (R-AR) repeatedly asked Chew — who is Singaporean — whether he was a member of the Chinese Communist Party. 

In multiple congressional testimonies, Chew has stressed that US users’ data is stored in the United States and isn’t accessible by ByteDance employees in China. The effort to completely wall off US user data began in 2022 under Project Texas, which TikTok has described as an “unprecedented initiative dedicated to making every American on TikTok feel safe, with confidence that their data is secure and the platform is free from outside influence.” But several reports, including one published by Fortune earlier this month, suggest that Project Texas hasn’t totally limited ByteDance’s access to US users’ data.

As Forbes notes, the Committee on Foreign Investment in the United States — which includes the head of the Department of Homeland Security, which oversees CBP — has been investigating ByteDance since 2019. In 2023, the committee recommended that the US ban TikTok unless ByteDance sells the app. Last week, President Joe Biden signed a foreign aid package that includes legislation that would ban TikTok unless ByteDance divests from it within the year.

CBP and TikTok did not respond to The Verge’s requests for comment.