The agency, using a combination of jawboning, stealth and legal force, has turned the nation’s Internet and telecommunications companies into collection partners, installing filters in their facilities, serving them with court orders, building back doors into their software and acquiring keys to break their encryption.
But even that vast American-run web is only part of the story. For decades, the N.S.A. has shared eavesdropping duties with the rest of the so-called Five Eyes, the Sigint agencies of Britain, Canada, Australia and New Zealand. More limited cooperation occurs with many more countries, including formal arrangements called Nine Eyes and 14 Eyes and Nacsi, an alliance of the agencies of 26 NATO countries.