hese programs were never about terrorism. They are not effective for terrorism. But they are useful for a lot of other things, like espionage, diplomatic manipulation, and ultimately social control.

Imagine yourself sitting at a desk, and you have a little box that lets you search anybody's email in the world; it lets you pull up their entire web history, anything they've ever typed into a search engine; you can read the message they are typing on Facebook as they do it; you can turn on the webcam on any private home; you can follow where anyone goes through their cell phone at any time. This is obviously an extraordinarily valuable mechanism of influence, of power, of capability.

What it doesn't do, though, is stop terrorist attacks.