US intelligence chiefs have confirmed that the National Security Agency has [performed] warrantless searches on Americans' communications. The NSA's collection programs are ostensibly targeted at foreigners, but in August the Guardian revealed a secret rule change allowing NSA analysts to search for Americans' details within the databases. Now, in a letter to Senator Ron Wyden, an Oregon Democrat on the intelligence committee, the director of national intelligence, James Clapper, has confirmed the use of this legal authority to search for data related to US persons". The legal authority to perform the searches, revealed in top-secret NSA documents provided ... by Edward Snowden, was denounced by Wyden as a "backdoor search loophole." Many of the NSA's most controversial programs collect information under the law affected by the so-called loophole. These include Prism, which allows the agency to collect data from Google, Apple, Facebook, Yahoo and other tech companies, and the agency's Upstream program - a huge network of internet cable taps. Confirmation that the NSA has searched for Americans' communications in its phone call and email databases complicates President Barack Obama's initial defenses of the broad surveillance in June. Wyden and Udall [said] "Today's admission by the Director of National Intelligence is further proof that meaningful surveillance reform must include closing the back-door searches loophole and requiring the intelligence community to show probable cause before deliberately searching through ... the communications of individual Americans."