The US communications regulator voted to revoke China Telecom’s license in America for reasons of national security, Washington’s latest move against what it sees as possible infiltration by Chinese companies into key networks.

The Federal Communications Commission (FCC) decision means China Telecom Americas must stop providing services in the United States within 60 days. China Telecom, China’s largest telecommunications company, has provided telecommunications services in the United States for nearly 20 years.

The news sent shares of US-listed Chinese tech companies plummeting, and their Hong Kong shares also saw significant sell-offs, causing the Hang Seng Index to drop more than 1%.

The Hang Seng tech index lost more than 3% and hit major players such as Tencent, Alibaba, and XD.