U.S. FBI Director Christopher Wray testifies before a Senate Homeland Security and Governmental Affairs hearing on threats to the United States, on Capitol Hill in Washington, U.S. Oct. 31. Reuters-Yonhap

The United States has seen North Korea, China and Russia employing cyber operations to target American research, the Federal Bureau of Investigation (FBI) chief said Tuesday.

FBI Director Christopher Wray made the remarks in a statement prepared for a session of the Senate Committee on Homeland Security and Government Affairs, noting that cybercriminal actors continue to "innovate" by using unique techniques to compromise U.S. networks.

"In the last few years, we have seen the People's Republic of China (PRC), the Democratic People's Republic of Korea and Russia use cyber operations to target U.S. research," Wray said, referring to North Korea and China by their official names.

The remarks came amid persistent reports that the North has been engaging in illicit cyber activities, including stealing cryptocurrency, as part of efforts to bankroll its nuclear and missile programs.

Wray said that his agency has seen China working to obtain controlled dual-use technology while developing an arsenal of advanced cyber capabilities that can be used against other countries in the event of a real-world conflict.

Moreover, he highlighted the "disruptive" impact that a serious supply-chain compromise can have through cyber intrusions that he said were conducted by Russia.

"As these adversaries become more sophisticated, we are increasingly concerned about our ability to detect specific cyber operations against U.S. organizations," he said. "One of the most worrisome facets is their focus on compromising U.S. critical infrastructure, especially during a crisis."

The director underlined the need to make it "harder and more painful" for malicious cyber actors and criminals to carry on their activities.

"We must impose consequences on cyber adversaries, and use our collective law enforcement and intelligence capabilities to do so through joint and enabled operations sequenced for maximum impact," he said.

As for foreign intelligence threats, Wray said that China, Russia and Iran are becoming "more aggressive and more capable than ever before," while noting that these countries seek to undermine the U.S.' core democratic, economic and scientific institutions.

Wray, in particular, said that the "greatest long-term threat" to the U.S.' ideas, innovation and economic security is the foreign intelligence and economic espionage threat from China.

"When it comes to economic espionage, the PRC uses every means at its disposal, blending cyber, human intelligence, diplomacy, corporate transactions, and other pressure on U.S. companies operating in the PRC, to steal our companies' innovations," he said.

Regarding the potential threat from the Hamas militant group, Wray said his agency has no information to indicate that the group has the intent or capability to conduct operations inside the U.S. though it "cannot and does not" discount that possibility.

"But we are especially concerned about the possibility of Hamas supporters engaging in violence on the group's behalf," he said. (Yonhap)