Around that time, Chinese spies compromised National Security Agency surveillance in Taiwan — an island Beijing claims

Around that time, Chinese spies compromised National Security Agency surveillance in Taiwan — an island Beijing claims
is part of China — by infiltrating Taiwanese intelligence, an American partner, according to two former officials.
All told, the Chinese killed or imprisoned 18 to 20 of the C. I.A.’s sources in China, according to two
former senior American officials, effectively unraveling a network that had taken years to build.
Mr. Kelton often mentioned Mr. Kelley’s mistreatment in meetings during the China episode, former colleagues say,
and said he would not accuse someone without ironclad evidence.
The number of American assets lost in China, officials said, rivaled those lost in the Soviet Union
and Russia during the betrayals of both Aldrich Ames and Robert Hanssen, formerly of the C. I.A.
At the time, the quality of the C. I.A.’s information about the inner workings of the Chinese government was the best it
had been for years, the result of recruiting sources deep inside the bureaucracy in Beijing, four former officials said.
From the final weeks of 2010 through the end of 2012, according to former American
officials, the Chinese killed at least a dozen of the C. I.A.’s sources.
spying operations in the country starting in 2010, killing or imprisoning more than a dozen sources over two years
and crippling intelligence gathering there for years afterward.