T-Mobile has been hacked by a Chinese cyber-espionage operation that hit multiple US and international telecom companies.

As reported by the Wall Street Journal, T-Mobile has become the latest carrier to be hacked by China.

The WSJ reported that hackers, linked to a Chinese intelligence agency, were able to breach T-Mobile as part of a months-long campaign to spy on the cellphone communications of high-value intelligence targets.

“T-Mobile is closely monitoring this industry-wide attack, and at this time, T-Mobile systems and data have not been impacted in any significant way, and we have no evidence of impacts to customer information,” T-Mobile said in a statement. “We will continue to monitor this closely, working with industry peers and the relevant authorities.”

The reported attack on T-Mobile follows reports of similar attacks against other US telcos last month including AT&T, Verizon, and Lumen Technologies.

The WSJ noted that the hackers were able to infiltrate US telecom infrastructure by exposing vulnerabilities in Cisco Systems routers, while investigators suspect the hackers relied on AI or ML to further their espionage operations, according to people familiar with the matter.

Last week, the Federal Bureau of Investigation (FBI) and the US cyber watchdog agency CISA said China-linked hackers were able to intercept surveillance data intended for American law enforcement agencies.

The FBI, which is investigating the hacks, said that the hackers had targeted government or political activity.

Beijing has previously denied the attacks on the US carriers.