WASHINGTON, D.C.: U.S. lawmakers are turning up the heat on China's biggest telecom firms, issuing subpoenas to compel their cooperation in an investigation into national security risks tied to their U.S. operations.

The House of Representatives select committee on China has invoked its rarely used subpoena power to demand answers from China Mobile, China Telecom, and China Unicom. The bipartisan effort seeks clarity on whether these state-linked firms could exploit their cloud and internet businesses in the U.S. to support the Chinese government or military.

Lawmakers are especially concerned about the companies' potential access to sensitive American data and critical infrastructure, even after the Federal Communications Commission revoked their licenses to operate U.S. telecom services between 2019 and 2022.

Despite those bans, the companies maintain a limited presence in the U.S., including routing internet traffic and offering cloud services that fall outside FCC licensing requirements. Lawmakers argue this creates serious oversight gaps.

"These platforms have enabled cyber intrusions, data theft, and potential sabotage of U.S. infrastructure," a committee spokesperson said, citing reports from private-sector sources and intelligence findings.

The subpoenas follow repeated attempts by the committee's chair, Republican John Moolenaar, and ranking Democrat Raja Krishnamoorthi, to obtain voluntary responses from the firms after a 2024 Reuters investigation revealed they were under Commerce Department scrutiny. Those requests went unanswered, prompting the committee's latest move.

In letters dated April 23, the lawmakers pointed to evidence suggesting the telecom giants may still operate network infrastructure, data centers, and cloud services in the U.S. through subsidiaries or affiliates. They demanded full cooperation by May 7.

China's embassy in Washington has pushed back, criticizing what it called the U.S. government's use of national security "as a pretext to suppress Chinese companies."

The lawmakers' actions come amid heightened scrutiny following alleged cyberattacks by China, including the "Volt Typhoon" operation that the FBI said targeted American telecommunications, energy, and water networks. Beijing has denied any involvement.

The companies and China's embassy did not immediately respond to Reuters' requests for comment.

If the firms continue to resist the investigation, Congress may consider holding them in contempt, escalating a battle that touches on trade, cybersecurity, and the broader U.S.-China rivalry.