Remember Echelon? For a few years the NSA's global surveillance operation was all the outrage. Why the NSA should not be spying on U.S. citizens, even via an international set up like Echelon. Everyone knows the FBI is supposed to do domestic spying.
Then post 9/11 -- as has been well-documented -- everything changed. President Bush gave the NSA a secret OK to directly spy on international communications from the U.S. without even troubling the rubber stamp that is the Foreign Intelligence Surveillance Court.
The legal opinions justifying the NSA op remain classified, so don't go getting all uppity. This is for your own good.