I can't see this being technically feasible... the entire design principle behind the tcp/ip stack is to route around damaged/missing network links. You would

I can't see this being technically feasible... the entire design principle behind the tcp/ip stack is to route around damaged/missing network links. You would have to completely isolate the US to do this, unless I'm misunderstanding modern routing protcols. Even leaving one link open would allow (slow) traffic outside of the US... Granted, systems like the great firewall of China tend to work, but that's because there is infrastructure in place to handle it, it didn't just pop up one day.