Be Prepared... the meaning of the motto is that a scout must prepare himself by previous thinking out and practicing how to act on any accident or emergency so that he is never taken by surprise.
I believe, along with many others, that you must first ask for what you want before you can have it.
Given the level of anti-Americanism in the world, given the level of frustration with the United States throughout the Muslim world, you've got a homegrown attack or you have a nuclear explosion in the air that is not a test somewhere. Those are still the biggest threats out there.