Inside the obscure FBI unit that does the NSA's dirty work

In "Meet the Spies Doing the NSA's Dirty Work," Foreign Policy's Shane Harris digs into the operations of a little-known FBI unit tasked with doing the domestic surveillance no other intelligence agency can touch.

Interviews with current and former law enforcement officials, as well as technology industry representatives, reveal that the unit is the FBI's equivalent of the National Security Agency and the primary liaison between the spy agency and many of America's most important technology companies, including Google, Facebook, YouTube, and Apple.