The CIA did not always know who it was targeting and killing in drone strikes in Pakistan over a 14-month period, an NBC News review of classified intelligence reports shows.

About one of every four of those killed by drones in Pakistan between Sept. 3, 2010, and Oct. 30, 2011, were classified as "other militants,” the documents detail. The “other militants” label was used when the CIA could not determine the affiliation of those killed, prompting questions about how the agency could conclude they were a threat to U.S. national security.