Q told us who the "MOLE" was... Some were convinced that a mole within the C.I.A. had betrayed the United States. Others believed that the Chinese had hacked the covert system the C.I.A. used to communicate with its foreign sources. Years later, that debate remains unresolved.

https://www.google.com/amp/s/www.nytimes.com/2017/05/20/world/asia/china-cia-spies-espionage.amp.html