Chalmers Johnson considers the parallels between contemporary American foreign policy orthodoxy and the Domino Theory used to support the Viet Namese War, and tries to peer into the future. A nugget:
Let me begin by asking: What harm would befall the United States if we actually decided, against all odds, to close those hundreds and hundreds of bases, large and small, that we garrison around the world? What if we actually dismantled our empire, and came home? Would Genghis Khan-like hordes descend on us? Not likely. Neither a land nor a sea invasion of the US is even conceivable.
Would 9/11-type attacks accelerate? It seems far likelier to me that, as our overseas profile shrank, the possibility of such attacks would shrink with it.
Worth a read.