The Senate’s top Democrat is raising questions about the Transportation Security Administration’s use of the China-owned video app TikTok, citing potential national security concerns and a ban by the Department of Homeland Security.

Sen. Chuck Schumer raised the concerns in a letter Saturday to TSA Administrator David Pekoske, months after news reports that the U.S. government launched a national security review of the app, which is popular with millions of U.S. teens and young adults.

In his letter, Schumer said national security experts have raised concerns about TikTok’s collection and handling of user data and personal information, locations and other content. He also noted in the letter that Chinese laws compel companies to cooperate with China’s government and intelligence collection.

The New York Democrat also pointed to a Department of Homeland Security policy that prohibits TikTok on department-issued cellphones.

“Given the widely reported threats, the already-in-place agency bans, and the existing concerns posed by TikTok, the feds cannot continue to allow the TSA’s use of the platform to fly,” Schumer said in a statement to The Associated Press.

Over the last few months, the agency has posted a number of videos on TikTok — some of which have been re-shared on other social media platforms like Twitter and amassed hundreds of thousands of views.

Some of the videos are musical parodies about what can and can’t be brought on an aircraft, while others advertise services like TSA’s expedited screening program known as PreCheck. In one of the videos, a TSA spokeswoman with Nutella spread on her face is showing different containers of the chocolate-hazelnut spread to detail which one can be brought in carry-on luggage.

A spokesperson for the TSA did not immediately respond to an email seeking comment.

(AP)