According to figures compiled by the New America Foundation, drone attacks aimed at suspected militants are estimated to have killed between 1, 900 and 3, 200 people in Pakistan over the past eight years.

CNN: A dangerous new world of drones

At the New America Foundation, we maintain an up-to-date database of every reported drone strike in Pakistan's tribal regions since 2004.

CNN: CIA drone war in Pakistan in sharp decline

The New America Foundation estimates that between 1, 953 and 3, 279 have been killed by drone attacks in Pakistan alone, of whom roughly one in 10 were civilians.

BBC: Drones at the forefront of the Brennan hearing