The government of the United States of America has confirmed that China-linked hackers breached several telecommunication service providers to steal wiretap data.

PRC-affiliated individuals compromised networks at “multiple telecommunications companies” in the United States as part of “a broad and significant” cyber espionage effort, according to a joint statement released by CISA and the FBI on Wednesday.

The Wall Street Journal reports that AT&T, Lumen (formerly CenturyLink), and Verizon are among the telecom carriers whose networks were compromised; however, neither CISA nor the FBI named the compromised organizations.

READ ALSO: Apple warns iPhone users of possible spyware attacks in 98 countries

Chinese hackers were able to obtain “internet traffic from internet service providers that count businesses large and small, and millions of Americans, as their customers” because they were able to access the networks “for months or longer,” according to the WSJ.

“The Federal Bureau of Investigation (FBI) and the Cybersecurity and Infrastructure Security Agency (CISA) continue to render technical assistance, rapidly share information to assist other potential victims, and work to strengthen cyber defenses across the commercial communications sector,” the agencies said. “We encourage any organization that believes it might be a victim to engage its local FBI Field Office or CISA.”