JOIN USThe National Security Agency tracks the locations of nearly 5 billion cellphones every day overseas, including those belonging to Americans abroad, The Washington Post reported.
The NSA inadvertently gathers the location records of "tens of millions of Americans who travel abroad" annually, along with the billions of other records it collects by tapping into worldwide mobile network cables, the newspaper said in a report on its website yesterday.
Such data means the NSA can track the movements of almost any cellphone around the world, and map the relationships of the cellphone user.
The Post said a powerful analytic computer program called CO-TRAVELER crunches the data of billions of unsuspecting people, building patterns of relationships between them by where their phones go. That can reveal a previously unknown terrorist suspect, in guilt by cellphone-location association, for instance.
The program is detailed in documents given to the newspaper by former NSA systems analyst Edward Snowden. The Post also quotes anonymous NSA officials explaining the program, saying they spoke with the permission of their agency.
Shawn Turner, a spokesman for the Office of the Director of National Intelligence, declined to comment on the report.
The DNI's general counsel, Robert Litt, has said that NSA does not gather location data on US cellphones inside the US but NSA Director Keith Alexander testified before Congress his agency ran tests in 2010 and 2011 to see if it was technically possible to gather such US cell-site data.
Alexander said that the information was never used for intelligence purposes and that the testing was reported to congressional intelligence committees.
But senator Ron Wyden, a Democrat and a member of the Senate Intelligence Committee, said at the time that Alexander could have explained more. "The intelligence leadership has decided to leave most of the real story secret," Wyden said, though he would not elaborate on the extent of the program. Wyden is among a bipartisan group of lawmakers who have introduced legislation to trim NSA's surveillance powers.
Alexander and other NSA officials have explained that when US data is gathered "incidentally" overseas, it is "minimized," meaning that when an NSA analysts realize they are dealing with a US phone number, they limit what can be done with it and how long that data can be kept.
Rights activists say those measures fall short of protecting US privacy.
"The scale of foreign surveillance has become so vast, the amount of information about Americans 'incidentally' captured may itself be approaching mass surveillance levels,'" said Elizabeth Goitein of the Brennan Center for Justice's Liberty and National Security Program.