U.S. senators urged the Federal Communications Commission (FCC) to address surveillance threats posed by foreign corporations managing U.S. telecommunications providers.

In the letter, led by Senator Ron Wyden and signed by Senators Dick Durbin, Richard Blumenthal, Chris Van Hollen and Ed Markey, claimed the U.S. government has not yet accounted for risks from foreign companies that operate or maintain U.S. networks, and there is not a comprehensive accounting of how many foreign companies provide such services to U.S. networks.

“It is a widespread practice in the wireless industry, particularly among small rural carriers, to outsource the installation and ongoing administration of networking technology to managed service providers, some of which are based in foreign countries. Many of these foreign service providers are subject to foreign surveillance laws, and as such, could be forced to abuse their access to U.S. networks to help foreign intelligence services spy on American subscribers,” the senators wrote to Acting Chairwoman Jessica Rosenworcel.

The FCC has taken action in recent years to address concerns raised by U.S. telecommunications firms using hardware made by foreign companies.

In March, for instance, the FCC designated five Chinese companies — Huawei, ZTE, Hytera Communications Corp, Hangzhou Hikvision Digital Technology Co and Zhejiang Dahua Technology Co — as a threat to national security under a 2019 law aimed at protecting U.S. communications networks.

For more information on the FCC’s ban on Chinese camera and video surveillance components, click here.