China killed or imprisoned 18-20 CIA sources

A massive intelligence breach occurred from 2010 to 2012 and it allowed the Chinese government to help clean out its ranks of CIA spies.

The Chinese killed at least a dozen CIA sources fro 2010-2012 and imprisoned a half-dozen more, according to the New York Times. One was shot in front of his colleagues in the courtyard of a government building as an example.

Investigators still aren't sure whether a spy within the CIA betrayed the sources or if the Chinese hacked the CIA's systems.

Since 2013, the US has been trying to rebuild its spy network there.

More at the NYT.