Republican Senator Josh Hawley on Wednesday said he will introduce legislation banning federal employees from using social media app TikTok on their devices, adding to growing tensions between Washington and Beijing over trade and technology transfers.

Hawley said the proposed ban would apply to government-issued devices.

Already, several US agencies that deal with national security and intelligence issues have banned employees from using the app, which has been rapidly growing in popularity among US teenagers and allows users to create short videos.

About 60 percent of TikTok’s 26.5 million monthly active users in the US are between the ages of 16 and 24, the company said last year.

In November, the U.S. government launched a national security review of TikTok owner Beijing ByteDance Technology’s $1 billion acquisition of U.S. social media app Musical.ly.

Hawley’s plan demonstrates broader concerns among lawmakers about collection and sharing of data on US users with the Chinese government. Many lawmakers are generally skeptical of China and see it as a threat to free speech and online privacy and security.