US ambassador to China and diplomat in Asia targeted in recent cyberattack: Sources

The U.S. ambassador to China, Nicholas Burns, and the State Department's Assistant Secretary for East Asia Daniel Kritenbrink's email accounts were breached by China-based hackers in the massive cyberattack that began in May and was discovered in mid-June, according to U.S. officials familiar with the investigation into the matter.

The hackers are not believed to have gained access to any classified information, but this revelation -- which was first reported by the Wall Street Journal -- adds to the fallout.

Secretary Blinken's account is not believed to have been breached. The hack was uncovered shortly before his trip to China where he was accompanied by Kritenbrink.

"For security reasons, we will not be sharing additional information on the nature and scope of this cybersecurity incident at this time. The Department continuously monitors and responds to activity of concern on our networks," a State Department spokesperson said. "Our investigation is ongoing, and we cannot provide further details at this time."

This is a developing story. Please check back for updates.