Obama: Civilian drone deaths 'haunt us'
23 May 2013 Last updated at 20:15 BST
President Barack Obama has said that before approving any drone strike, there must be "near-certainty" civilians will not be hurt, in a major national security speech.
But, speaking at the National Defence University, Washington DC, the president said it was a "hard fact" that innocent lives had been lost.
Mr Obama said: "For me, and those in my chain of command, these deaths will haunt us as long as we live."