The National Security Agency is secretly tapping into Yahoo and Google data centers, and accessing much more information than previously thought. The Washington Post broke the news after analyzing more documents taken from the NSA by former analyst Edward Snowden. The revelations raise questions of whether the NSA is breaking federal wiretap laws. In response, the agency says it does not use the method to collect vast quantities of data on Americans. And it says it is not using a presidential order to get around limitations imposed by the Foreign Intelligence Surveillance Act.