A former employee of the company that controls TikTok told Sen. Josh Hawley (R-MO) that members of the Chinese Communist Party can access data from American users of the social media platform.

The allegations occur as TikTok, which is owned by Chinese technology company ByteDance, faces scrutiny for national security concerns and reported data privacy breaches. Hawley said in a letter sent to Treasury Secretary Janet Yellen on Tuesday that employees, including members of the Chinese Communist Party who are on the company’s payroll, can allegedly switch between Chinese and American data with “nothing more than the click of a button.”