Asked about the existential threats against Washington, Undersecretary of Defense for Policy Michele Flournoy said there were many, but warned that "the thing that keeps me awake at night is a nexus between terrorism and massive destruction."

She told a Washington symposium on US security that the United States needs to better prepare for "the possibility that a terrorist organization could either acquire a ready-made weapon or fabricate something improvised that would have a catastrophic effect for us." [ YAHOO NEWS ]