“On December 10 [2001], the U.S. National Security Agency, which sucks up signals intelligence around the world, picked up an important intercept from Tora Bora [Afghanistan]: ‘Father (bin Laden) is trying to break through the siege line.’ This was then communicated to the Delta [Force] operators on the ground. Around 4 p.m. the same day, Afghan soldiers said that they had spotted bin Laden and had him surrounded. Later that evening another intercept was picked up of bin Laden talking on the radio with some of his lieutenants… The information was so accurate that it appeared to pinpoint bin Laden’s location down to within ten meters. Another intercept that same night placed him two kilometers further away, suggesting that the al-Qaeda leader was on the move.”
– Peter Bergen, The Longest War, Page 76