Some argue that the American government (of every shade) has been using fear to get the populace to do what they want pretty much since the Founders. The ones within our lifetime include Communists, terrorists, drug lords, etc but back before it was the British, the Spanish, etc.

However I would agree that the whole of American culture (and many others including increasingly so British) is so steeped in fear they wouldn't know how to cope without an 'enemy'.

Have a read of the wikipedia entry Culture of Fear (http://en.wikipedia.org/wiki/Culture_of_fear).