I think you misunderestimate the power of nuclear and/or biological weapons.
One rogue nation, such as Iran perhaps, or North Korea, or Syria, could develop a virulent undefensible strain of smallpox, bubonic plague, and send it into each American city.
We could all be dead within a month.
Or perhaps Pakistan gets taken over by radical Islamofascists, and sends agents armed with miniature nuclear bombs into the biggest 25 American cities.
Maybe the blasts would not "destroy" us as you say, but the resulting fallout would stop all civil liberties, not to mention free travel between the states.
Need I paint a more dire picture of what ONE single rogue nation could unleash on America.
Well, thank God! Another realist on this thread.
HELL NO!
Let the nukin' and pavin' begin!
I yield to you, MojoWire, should we proceed through the ME west to east or east to west? (/sarcasm)