who helped break this story and ari fleisher in just a moment. has this actually been used to prevent a terror attack that we know of? >> this has been used very successfully in terms of two things. one, it has detected nascent plots in progress and provided the lead material and intelligence to get in front of those plots. on a more substantive level, it caught a plot at the very last minute and saved new york city from a series of bombings. one day, september 6th at 7:58 a.m. in 2009, as it was dawn in colorado, an e-mail went from aurora, colorado from an apartment complex to a selector that was in pakistan. this belonged to an al qaeda master planner, bomb maker, and the e-mail basically said i'm having trouble with the recipe, i need to know how much yeast and how much flour to use. this was code for a bomb-making recipe that wasn't working for a