The House of Representatives has banned staff members from using WhatsApp on government devices, according to a report from Axios. In an email viewed by the outlet, the House’s chief administrative officer (CAO) tells staffers that the Office of Cybersecurity “has deemed WhatsApp a high-risk” because of a “lack of transparency in how it protects user data, absence of stored data encryption, and potential security risks.”

The email says that congressional staff members can’t download or use the mobile, desktop, or web browser version of WhatsApp on any government device. “If you have a WhatsApp application on your House-managed device, you will be contacted to remove it,” the email reads.

Meta communications director Andy Stone pushed back against the decision in a post on X, saying the company disagrees with the CAO’s characterization of WhatsApp “in the strongest possible terms.” Stone adds that messages on WhatsApp are end-to-end encrypted by default, meaning third parties — not even Meta, which owns the platform — can read them. “This is a higher level of security than most of the apps on the CAO’s approved list that do not offer that protection,” Stone writes.

As noted by The Guardian, the CAO’s message to staff recommended that they use other apps for communications instead, such as Microsoft Teams, Signal, iMessage, FaceTime, or the Amazon-owned messaging service Wickr. The CAO didn’t immediately respond to The Verge’s request for more information.