The Chinese government “systematically dismantled” CIA spying operations in China starting in late 2010 and killed or imprisoned at least a dozen CIA sources over the next two years, The New York Times reports.
The newspaper cited 10 current and former US officials, who described the intelligence breach as one of the worst in decades. They spoke on condition of anonymity.
The report said US intelligence and law enforcement agencies scrambled to stem the damage, but were bitterly divided over the cause of the breach.
Some investigators were convinced there was a mole within the CIA, while others believed the Chinese had hacked the covert system the CIA used to communicate with its foreign sources.
The debate remains unresolved, the paper said.