Much like the agency's PRISM program, the GPS program collects a substantial amount of Americans' data "incidentally."
The Post, drawing on documents form Edward Snowden and interviews with intelligence officials, reports that
The ability to retrace someone's movements provides an astonishing ability to map that peron's entire life, as seen by the metadata published by German politician Malte Spitz.
One senior collection manager told The Post that the agency is "getting vast volumes" of location data from around the world by tapping into the cables that connect mobile networks globally.
U.S. officials insisted to the Post that the location data programs are lawful and only used for intelligence on foreign targets.
The Post reports that the NSA collects locations in bulk and then uses powerful analytic tools - known collectively as CO-TRAVELER - to "map cellphone owners' relationships by correlating their patterns of movement over time with thousands or millions of other phone users who cross their paths."The result is astonishing, since in can both track metadata of a target while also seeing the general public and "co-travelers," or those who may be associates with the target.
The issue for privacy advocates and concerned citizens, ACLU technologist Chris Soghoian explained to the Post, is that "the only way to hide your location is to disconnect from our modern communication system and live in a cave."
Furthermore, the Obama administration has argued in court that Americans have no Fourth Amendment right to privacy when it comes to GPS location data.
The Post notes that number of Americans whose locations are tracked is unclear Snowden documents alone, and that senior intelligence officials declined to offer an estimate.