Shane Harris explains how the "most highly classified personnel records in the entire government" may have been linked to the Office of Personnel Management database that was successfully targeted by hackers.
"In 2010, officials across the government were under pressure to chip away at a backlog in processing security-clearance applications. And a sweeping intelligence law, passed in the wake of the 9/11 attacks, required them to merge their records into one all-purpose security-clearance system... intelligence officials were particularly concerned that names, Social Security numbers, and personal information for covert operatives would be exposed to hackers if the personnel database, known as Scattered Castles, weren’t left to stand on its own."
"But three years later, the Office of the Director of National Intelligence began working with OPM 'to set the stage for the upload of active, completed clearance records' from OPM’s system—which was later overrun by hackers—into Scattered Castles... If there are connections between the two—as that recent government report suggests there are—it could be exploited by hackers."
Meanwhile, Robert Knake argues that the OPM data breach is not as big of a threat to U.S. intelligence as many have speculated.