The NSA, working with its British counterpart, the Government Communications Headquarters (GCHQ), secretly taps into the internal networks of Yahoo and Google, the two biggest Internet companies by overall data traffic. The operation intercepts information flowing between the enormous data centers that those companies maintain around the world. In general, Google and Yahoo use privately owned or leased lines to synchronize their data centers. This graphic shows how the NSA and GCHQ break into those internal networks, using Google’s as an example. Less is known about Yahoo’s networks, but the NSA operations are thought to be similar.
SOURCE: Staff reports; Google, www.google.com/about/datacenters.