Isn't it sad that since the NSA revelations it's very easy to speculate? It doesn't take much to stretch the imagination any longer.
EDIT: One intelligence agency, CIA, has already killed an American citizen[2].
1. http://www.guardian.co.uk/commentisfree/2013/feb/05/obama-ki... 2. http://www.washingtonpost.com/wp-dyn/content/article/2010/01...
http://en.wikipedia.org/wiki/Abdulrahman_al-Awlaki#Abdulrahm...
How is it a bit of a stretch to think an organization that powerful might kill someone?