I have never witnessed a political debate that was more ill informed and hypocritical than this one -- and I mean on all sides. It's just appalling.
The NSA's mission is secretive, but based on the writing of the best informed journalists, like Bamford, the NSA's primary mission is not counter terrorism. There aren't enough terrorists in the world to justify its size and what it does. In Bamford's 2001 book, there isn't even a mention of terrorism nor an entry in the index about terrorism or Osama bin Laden -- although Bamford wrote a hasty addendum because the book came out shortly after 9/11.
