>It would be easy. Require the backbone CEO's to certify that their networks don't connect to networks that connect to China, Russia, Nigeria, etc.

And when other countries don't play ball? Then we shut down those backbones, and it's the United States that is isolate, not Russia (though please feel free to pick another target if you don't like Russia). No one's cutting off China, not without their economy dropping dead. Sure, maybe there's some country that you could do this to... but that country is so unimportant that they're probably already almost-cut-off anyway. You don't even get to to do this to a Brazil or Indonesia, let alone any country that matters.

Yeah, exactly. They were cut off from SWIFT and yet they do ample international trade. These think tank ideas from "domain experts" and political types rarely work in the real world. Russia, China and others do the same, block stuff - but people get the content, products, etc anyways.