Hackers linked to the Chinese government are targeting critical infrastructure in the United States, preparing to cause “real-world harm” to Americans, FBI director Christopher Wray plans to tell a House of Representatives panel.

Water treatment plants, the electrical grid, oil and natural gas pipelines and transportation hubs are among the targets of state-sponsored hacking operations that have received “far too little public focus,” Wray will testify to the House select committee on competition with China on Wednesday.

“China’s hackers are positioning on American infrastructure in preparation to wreak havoc and cause real-world harm to American citizens and communities, if or when China decides the time has come to strike,” Wray will tell the panel, according to a portion of his testimony released by the FBI.

The Chinese foreign ministry did not immediately respond to a request for comment on the matter.

Wray is scheduled to make his first appearance before the House China committee on Wednesday at a hearing focused on cyber threats posed by Beijing. He will appear alongside three other top US cyber officials.

Wray’s warning comes a day after Reuters reported that the US government launched an operation in recent months against a Chinese hacking operation, Volt Typhoon, that officials said had been spying on US infrastructure networks.

Wray has repeatedly said the Chinese government is trying to undermine the United States through espionage campaigns, intellectual property theft and cyber attacks.

The Chinese government has previously accused the US and its allies of spreading “disinformation” through its accusations against what Washington says are state-sponsored hacking groups.

-Reuters