The US National Security Agency has been exploiting US citizens' personal information drawn from its large collection of metadata to create complex graphs of social connections for foreign intelligence purposes, the latest Snowden leaks have revealed.

Documents obtained by the New York Times from the former NSA contractor Edward Snowden say that the practice has been going on since November 2010, after restrictions prohibiting the agency from working with US citizens’ data were “lifted” by NSA officials.

The NSA was then authorized to conduct “large-scale graph analysis on very large sets of communications metadata without having to check foreignness” of the e-mail addresses, phone numbers or any other identifiers, the documents reportedly said.

The policy shift was intended to help the agency “discover and track” connections between intelligence targets overseas and people in the US, a January 2011 NSA memorandum cited in the documents explained.

According to the report, the agency has been allowed to “enrich” their communications data with materials obtained from public, commercial and other sources while preparing the graphs. Such sources reportedly include Facebook profiles, bank codes, insurance information, passenger manifests, voter registration rolls and GPS location information, as well as property records and unspecified tax data.



The sophisticated graphs provide the agents with direct and indirect “contact chains” between an unspecified number of Americans and people or organizations overseas that are of foreign intelligence interest, the report says.

Not only do they identify the list of possible associates, but also note their locations at certain times, their traveling companions and other personal information, it adds.

The documents provided no information on the results of the NSA surveillance. According to the NYT, the agency’s officials declined to say how many Americans have been caught up in the effort.

The NSA has denied it abuses its practice of vast data collection, which includes the private information of the US citizens, with the agency’s spokeswoman saying that “all of NSA’s work has a foreign intelligence purpose” and that “all data queries must include a foreign intelligence justification.”

In justifying the warrantless analysis of metadata on US soil, the spokeswoman referred to a 1979 Supreme Court ruling saying that Americans could have no expectation of privacy about what numbers they had called.



When asked whether the NSA collects Americans’ locations based on cell phone signals data, the agency’s director Keith B. Alexander on Thursday told a Senate Intelligence Committee that the agency was not doing so as part of the the Patriot Act, but added that a fuller response would be classified.

While the agents are said to be allowed to analyze the metadata, but not the contents of the calls or e-mails, the experts argue that this information alone is enough to produce a portrait of a person based on his contacts, as well as to pick up some sensitive details of an individuals's private life.



“Metadata can be very revealing. Knowing things like the number someone just dialed or the location of the person’s cellphone is going to allow to assemble a picture of what someone is up to. It’s the digital equivalent of tailing a suspect,” Orin S. Kerr, a law professor at George Washington University, told the NYT.

The leaked documents, which are said to provide a rare window into what the NSA actually does with the information it gathers, and how it unlocks “as many secrets about individuals as possible,” are the latest revelations obtained via former CIA employee and NSA contractor Edward Snowden.



In the US, Snowden is wanted on espionage charges for leaking classified documents that focused on the massive electronic surveillance by the US government and its foreign allies which collaborated with the NSA.



Snowden was granted temporary asylum in Russia on August 1 after being stuck in a transit zone of Moscow’s Sheremetyevo airport for more than a month. He is now staying in an undisclosed location, with reports saying he has done some travel and already speaks some Russian.

