The hack of millions of U.S. government personnel files, and allegations that the attack may have originated in China, will put cybersecurity at the top of the upcoming U.S.-China summit later this month, according to news reports.
The breach of computer systems of the Office of Personnel Management was disclosed Thursday by the Obama administration, which said records of up to 4 million current and former federal employees may have been compromised.
Investigators “are aware of the threat that is emanating from China,” White House spokesman Josh Earnest said Friday.
“We know that the attack occurred from somewhere in China, but we don't know whether it was an individual or a group or a nation-state attack,'' Representative Jim Langevin, a leading voice in Congress on cybersecurity, was quoted as saying by The Associated Press.
Accusations called 'irresponsible'
China’s Foreign Ministry spokesman Hong Lei called the accusations “irresponsible” and noted that China also is a victim of cyberattacks.
Accusations of a Chinese role in the attack, including possible state sponsorship, could further strain ties between Washington and Beijing.
Tensions are already heightened over Chinese assertiveness in pursuit of territorial claims in the South China Sea.
The hacking also raises questions about how the United States would respond if it confirmed that the Chinese government was behind it.
The U.S. national flag is pictured at the Office of Personnel Management building in Washington, June 5, 2015.
Disclosure of the breach comes ahead of the annual U.S.-China Strategic and Economic Dialogue scheduled for June 22-24 in Washington, D.C.
Cybersecurity was already expected to be high on the agenda.
U.S. officials said the talks would proceed as scheduled, as would Obama's plans to host Chinese President Xi Jinping on a state visit to Washington in the fall.
"The Chinese have been saying privately, and somewhat in public, that we want the summit to go really well. 'Let's not talk about espionage. Let's talk about how we can work together,' " James Lewis, a cybersecurity expert at the Center for Strategic and International Studies think tank, was quoted by Reuters as saying.
"This might be a U.S. response to that: 'No, we are going to talk about espionage,’ ” Lewis said.
These are not the first large-scale cyberattacks allegedly traced to China.
Chinese hackers were also blamed for penetrating OPM's computer networks last year, The New York Times reported last July, citing unidentified U.S. officials.
In 2014, the FBI indicted five officers in China’s People’s Liberation Army for coordinating hacks on six U.S.-based corporations such as U.S. Steel and Alcoa.
Chinese officials have repeatedly denied any involvement in such attacks, saying the U.S. has never offered definitive proof of a hack directly traced back to Beijing.
Bruce Schneier, a leading cryptographer, said it’s very hard to trace attacks.
“When we can, it’s often because hackers have made mistakes in hiding their tracks and it’s not something we can do quickly,” Schneier told VOA in an interview earlier this year. “In other cases, we’ve known with reasonable assurance the attacks came from certain buildings and offices in China and that the government knew about it and approved it.”
VOA's Doug Bernard contributed to this report. Material from The Associated Press and Reuters was used in this report.