It seems as though we may be in very much the same situation that the Soviet Union is in. Al-Quiada alone did not bankrupt the Soviet Union, it was the Cold War and a combination of factors includign Al-Quiada giving them a bloody nose.
I still think that it's a bit of a remote possibility but lets not forget that the American Colonies were capable of stemming off the British Empire, albeit once we were backed by the French.