Comment
The Assassination of the Presidents and the Beginning of the "Apocalypse" :
http://www.gwu.edu/~nsarchiv/NSAEBB/NSAEBB119/index.htm
Information, Intelligence and the U.S. Response
http://www.gwu.edu/~nsarchiv/NSAEBB/NSAEBB117/index.htm
Evidence of inaction
http://www.gwu.edu/~nsarchiv/NSAEBB/NSAEBB53/press.html