Looking back at NSA revelations since the Snowden leaks

Aired: 12/12/2013 | 0:03:23 | Clip
Since 9/11, the activities of the National Security Agency have grown dramatically. Much of the NSA's work gathering intelligence was secret until documents leaked by Edward Snowden were published, revealing the agency had collected phone records from Americans and allies abroad. Margaret Warner reviews the disclosures so far.