The National Security Agency is the U.S. government's primary eavesdropping agency. It intercepts, decodes, and analyzes foreign communications — such as emails, telephone calls, and other "signals intelligence." The Fort Meade, Md.–based agency, which has an annual budget of about $10 billion and employs some 40,000 people, has long carried out this mission in the shadows. But a series of leaks by former agency contractor Edward Snowden has revealed the stunning scale of its global surveillance operation. It's now known that the NSA scoops up and stores billions of internet communications and cellphone records from the U.S. and around the world every day, which can then be studied by the agency's legion of code breakers, data miners, and counterterrorism specialists. When President Obama receives his daily intelligence briefing, "at least 75 percent" comes from the NSA's cyberspies, said Mike McConnell, director of national intelligence under President George W. Bush.
