Top US intelligence officials are revealing more about their spying in an effort to defend the National Security Agency from charges that it has invaded the privacy of Americans on a mass scale. But the latest disclosure—that the NSA tried to track law-abiding Americans' cell phone locations—is only adding to the concerns of lawmakers.
NSA chief Gen. Keith Alexander told Congress yesterday that his spy agency ran tests in 2010 and 2011 to see if it was technically possible to gather US cell-site data that can show where a cell phone user has traveled. Alexander says the information was never used and the testing was reported to congressional intelligence committees. He also denied reports that the NSA has mined Americans' social media. (Read more Keith Alexander stories.)