The Chinese government killed or captured at least 18 CIA sources between 2010 and 2012, the New York Times reported, destroying the agency's ability to collect intelligence throughout the country for years.
The agency has never discovered the cause of the intelligence breach, which could have been the result of a mole in the CIA's ranks, Chinese surveillance of covert communications methods or "sloppy American tradecraft," the Times wrote. The Chinese government killed at least 12 of the sources, one of whom was executed by gunshot in front of colleagues outside a government building.
Government officials told the paper the losses were roughly equivalent to the betrayals of CIA officer Aldrich Ames and FBI agent Robert Hanssen, who both sold out U.S. intelligence sources to the Russians in exchange for large amounts of cash. That the breach that allowed China to capture or kill so many U.S. spies was never discovered continues to concern the CIA, which has struggled to make inroads there due to an "extensive security apparatus" that makes developing sources extremely difficult.
A joint CIA-FBI investigation later identified a Chinese-American former CIA operative who left his job and moved to China as a possible suspect. Although the CIA was able to lure him back to the U.S. and question him in 2012, the man admitted no wrongdoing, and Chinese counter-intelligence services' luck apparently dried up in 2013.