The NSA's enormous surveillance system can access around three-quarters of all U.S. internet traffic, snaring in some cases even email sent between U.S. citizens and domestic web phone calls.
Programs with innocuous code names like Blarney, Fairview, Oakstar, Lithium and Stormbrew are established at major telecommunications companies like AT&T and Verizon. The NSA then asks the telcos to cut out swaths of data:
The systems operate like this: The NSA asks telecom companies to send it various streams of Internet traffic it believes most likely to contain foreign intelligence. This is the first cut of the data.
These requests don't ask for all Internet traffic. Rather, they focus on certain areas of interest, according to a person familiar with the legal process. "It's still a large amount of data, but not everything in the world," this person says.
The second cut is done by NSA. It briefly copies the traffic and decides which communications to keep based on what it calls "strong selectors"—say, an email address, or a large block of computer addresses that correspond to an organization it is interested in. In making these decisions, the NSA can look at content of communications as well as information about who is sending the data.
These new details about the nature and size of the NSA's spy efforts were gleaned from interviews with current and retired officials by Wall Street Journal reporters Siobhan Gorman and Jennifer Valentino-Devries, who have a bite-sized bullet-pointed rendition of their findings if reading an article seems like too much work.