Chinese hackers breached eight American telecommunications companies and obtained access to sensitive data for an extended period, a senior counterintelligence official revealed this week.

Michael C. Casey, director of the National Counterintelligence and Security Center which conducts damage assessments for the U.S. intelligence community, provided new details on the ongoing electronic penetrations by Chinese hackers dubbed Salt Typhoon.

“It’s quite bad,” Mr. Casey said in a video interview with The Wall Street Journal on Tuesday.

“At least eight U.S. companies have been breached; at least a dozen worldwide,” he said. “The PRC  actors have extensive access to the companies.”

The damage is said to be serious since the stolen information included requests for federal court surveillance. Such information would allow China to better mask its intelligence operatives or to pass disinformation to U.S. intelligence.

Mr. Casey, a former congressional intelligence staff director, said the hacking includes very broad access and, in some cases, specific high-profile people have been targeted and their messages, calls and in some cases call audio files have been obtained.

Metadata, or summary information that provides information about more detailed information, has been secured by Chinese hackers.

“However, there’s nothing actually stopping them from going after less targeted individuals, I’d say more common folks, other than their own restraint at this point,” he said. “They are still maintaining access to the system.”

Investigators from the FBI and Cybersecurity and Infrastructure Security Agency are investigating the breaches and continue to learn new details of the operation, Mr. Casey said.

Asked how the Chinese were able to gain access and whether it was the hackers’ expertise or weak security, Mr. Casey said both were factors.

“Frankly [the Chinese hackers] have gotten quite good over the years,” he said. “The fact that they’ve been able to get such broad access to so many companies and gain access to so many people’s records suggests that we need to up our game quite a bit.”

Mr. Casey said the case has highlighted the need to use encrypted messaging applications, something the federal security community and FBI recently said those seeking to secure their data should do.

The counterintelligence leaders said urging the public use of encryption is “a weird thing for the government to be saying given the history of where the FBI has been.”

The FBI in the past has complained that uncrackable secure communications limit its ability to gain valuable information from electronic communications needed for its law enforcement and counterintelligence probes.

American security efforts need to be increasing “across the board,” Mr. Casey said, as a result of increased use by intelligence services of multiple lines of attack – telecoms and other cyber penetrations, human agents inside organizations, and supply chain attacks.

“We’ve seen PRC actors try and get information from companies through investment activities, basically trying to invest in a company and doing due diligence to steal intellectual property theft,” he said. “And we’ve seen them do combinations of all the above.”

Mr. Casey also said China has launched another covert attack on American infrastructure dubbed “Volt Typhoon.” The operation breached key infrastructure facilities on the U.S. island of Guam, a major military hub in the Pacific and a target of Chinese missile threats.

“It’s still definitely a key effort. We see it all the time,” Mr. Casey said of Chinese targeting of infrastructure. “The belief is this preparation for a Taiwan scenario where they could affect critical infrastructure and slow down the U.S. military reaction.”

Asked about counterspy efforts for the incoming Trump administration, Mr. Casey said during the first administration a lot of effort was devoted to countering Chinese intelligence activities. “So I’m hoping those activities continue and are enhanced,” he said.

To better assist companies deal with foreign intelligence threats, the counterintelligence center is looking at setting up an office that can declassify threat information, Mr. Casey said.

The idea is unusual since intelligence agencies do not spend a lot of time thinking about what can be disclosed to the public.

“Candidly, we’ll see how well it works,” Mr. Casey said. “We often don’t have very granular information. You know, it’s never going to be that guy over there is like going to go steal the thing down the hall.”

• Bill Gertz can be reached at bgertz@washingtontimes.com.