DefenseKhaled Abdullah/Reuters In Yemen, tribesmen stand on the rubble of a building destroyed by a US drone air strike, that targeted suspected al Qaeda militants on Feb. 3, 2013.
The documents, released to the Guardian newspaper by former NSA contractor Edward Snowden and shared with The New York Times, also detail how often those strikes go wrong.
The documents also reveal that US forces conducted a strike in 2012 to kill a doctor, identified as Khadim Usamah, who the US believed was surgically inserting explosives into potential Al Qaeda operatives.
Britain's military has carried out drone strikes in war zones in Afghanistan, Iraq and Libya, but the documents suggest that British intelligence also helped guide strikes by the US outside of those zones.
Drone attacks carried out by the US have been heavily criticized in the past, and prompted thousands to protest against their use. Critiques say that drone attacks are not specific enough and often end up killing a lot of civilians.
Outcries against the use of drones were renewed when President Barack Obama disclosed in April that two Western aid workers who were held hostage by Al Qaeda had been killed after a strike against the terrorist group in Pakistan.
Instances in which civilians have been killed and uncertainty about drones' accuracy in hitting their target has led to increased public scrutiny of the use of drones. In the case of the hostages who were killed, intelligence officers were unaware they were present at the time of the strike.
Meanwhile, an Algerian terrorist who had been reported dead by the Pentagon after a strike appears to still be alive, according to the Times. And American officials only learned a few days after an attack in Yemen that they had killed the leader of Al Qaeda in the Arabian Peninsula.
Officials argue that missiles fired from unmanned aircrafts are the most precise way to target terrorists. But for the shots to be as precise as possible, the documents highlight the importance of surveillance and eavesdropping in order to determine not only the exact location, but also whether everyone in a strike zone poses a threat. The documents also detail how that use of technology is flawed.
Reuters / Fayaz Aziz Drone strikes have been wildly unpopular, sparking protests all around the globe.
The guide also says that whether a call was terminated right after a strike is a good way of knowing whether it hit its target.
Amid a parliamentary investigation into whether the UK was part of unmanned aerial vehicle strikes (UAV) in Yemen, British
But the new documents suggest that the country provided intelligence for different American strikes, including one in Yemen.
The NSA and CIA both declined to comment to the Times. But the GCHQ said in a statement that it expects "all states concerned to act in accordance with international law and take all feasible precautions to avoid civilian casualties when conducting any form of military or counterterrorist operations."
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