NSA official: mass spying has foiled one (or fewer) plots in its whole history

During an NPR interview, the NSA's outgoing deputy director John C Inglis -- the top civilian official in the NSA hierarchy -- admitted that the NSA's mass surveillance program had foiled a total of one terrorist plot (an attempt to wire some money to al-Shabaab in Somalia) in its entire history. But he doesn't want to get rid of his agency's program of spying on everything every American does, because it's an "insurance policy" in case someone tries the kind of terrorist attack that it might foil.

While Inglis conceded in his NPR interview that at most one terrorist attack might have been foiled by NSA’s bulk collection of all American phone data – a case in San Diego that involved a money transfer from four men to al-Shabaab in Somalia – he described it as an “insurance policy” against future acts of terrorism.
“I'm not going to give that insurance policy up, because it's a necessary component to cover a seam that I can't otherwise cover,” Inglis said.

NSA makes final push to retain most mass surveillance powers