A top U.S. cyber official warned Monday that Chinese hackers are likely to disrupt U.S. critical infrastructure, including pipelines and railways, if a conflict were to occur between the two nations, Reuters reported.

Jen Easterly, director of the Cybersecurity and Infrastructure Security Agency (CISA), said the Chinese government is heavily investing in ways to sabotage U.S. infrastructure.

“Given the formidable nature of the threat from Chinese state actors, given the size of their capability, given how much resources and effort they’re putting into it, it’s going to be very, very difficult for us to prevent disruptions from happening,” Easterly said during an event hosted by the Aspen Institute.

Her comments come amid rising tensions between the U.S. and China — including in cyberspace. 

Last month, U.S. intelligence agencies released a joint advisory based on a Microsoft report that found a Chinese state-sponsored cyber actor, known as Volt Typhoon, has been accessing credentials and network systems of critical infrastructure organizations in parts of the U.S., including the territory of Guam, which has a military base of strategic interest to the U.S.

Volt Typhoon, which has been active since mid-2021, has been targeting organizations in several sectors, including communications, manufacturing, utility, transportation, construction, maritime, government, information technology and education.

Microsoft said the hacking group, which mostly focuses on espionage and information gathering, is “pursuing development of capabilities that could disrupt critical communications infrastructure between the United States and Asia region during future crises.”

The tech giant also said the group’s objective is to spy on organizations and gain access to their networks “without being detected for as long as possible.”

Lawmakers also recently expressed their concern about Volt Typhoon’s malicious cyber activity. 

“We are extremely concerned by the news of Chinese state-sponsored malicious activity against U.S. critical infrastructure networks, and the activity in Guam is especially concerning considering the heightened risk to the U.S. military,” the lawmakers said in a statement.