As Americans learn more about the National Security Agency’s tracking operations, new revelations have emerged about just how closely the NSA may be watching individual digital footprints.

The New York Times reports that according to documents provided by former NSA contractor Edward Snowden, the agency is compiling billions of pieces of data a day in an effort to create "contact chains" linking Americans to those with whom they communicate and travel.

Much of the data used is publicly available -- but not all of it.

Relying on a 1979 Supreme Court ruling that there was no legitimate privacy expectation about phone numbers that Americans dial, the NSA has pursued policies to give it wider access to phone and email logs.

That information - grouped with things like Facebook profiles, tax and property records and GPS location data - has reportedly been collected by the agency since 2010 in so-called "social profiles."

When asked about the allegations, NSA spokeswoman Marci Green Miller said, "We know there is a false perception out there that the NSA listens to the phone calls and reads the e-mail of everyday Americans aiming to unlawfully monitor or profile U.S. citizens

"It's just not the case," she added.

Miller also said the agency's activities were "directed against foreign intelligence targets." However, that includes collecting information on Americans and their records, sometimes without a warrant.

White House Press Secretary Jay Carney weighed in Monday as well, saying the NSA's mission is "to protect the nation and its interests from threats such as terrorism and the proliferation of weapons of mass destruction."