The Transportation Security Administration (TSA) has banned employees from using TikTok to create posts for the agency.

According to a report in Time, the policy change came after Senator Chuck Schumer wrote a letter to the agency’s head pointing out concerns over the app, given the allegations it poses a threat to national security. The Pentagon has already instructed military personnel to avoid the app and the company behind TikTok is facing a lawsuit in which the app is alleged to have secretly recorded and uploaded videos to China.

In view of those concerns, Senator Schumer told the Associated Press, “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.”

TSA has said it never officially recommended or supported the app but, as Time points out, multiple TSA videos showed the TikTok logo. Since Senator Schumer’s letter, the agency has stated that a “small number of TSA employees have previously used TikTok on their personal devices to create videos for use in TSA’s social media outreach, but that practice has since been discontinued.”