McClatchy said its review of top-secret intelligence reports found hundreds of low-level militants killed by the drone strikes belonged to groups with no ties to al-Qaida and showed a higher level of uncertainty than the Obama administration has been willing to admit.
The use of unmanned Predator and Reaper drones began in 2007 under President George W. Bush. Obama continued the drone strikes, promising they would be used precisely and in limited circumstances.
"It has to be a threat that is serious and not speculative," Obama told CNN this past Sept. 6. "It has to be a situation in which we can't capture the individual before they move forward on some sort of operational plot against the United States."
McClatchy said it found that in the year ending in September 2011 only six senior al-Qaida leaders were killed by drone strikes. But U.S. intelligence agencies estimated 482 individuals were killed by drones in that year, at least 265 of them "assessed" as extremists from Afghanistan, Pakistan and elsewhere.
Some of the targets were suspected of being involved in militant activity.