One thought--

Militaries have certainly considered cyber attack scenarios and developed strategies to keep their military working via intranets. Intranet communications independent of the large IP and DNS systems, for example.

But they likely haven't figured out how to deal with a large scale outage for a population of tens of millions, even hundreds of millions of people. When the IP system or DNS system goes down, there's no quick fix for millions of independent users. There just isn't.

China, being centralized, is probably better prepared at recovering connectivity for its population, at least in major cities. The US? I don't know. It would depend on to what extent they've prepared for such an attack with the main ISPs.

I wouldn't be too optimistic.

PS: Remember the old days of broadcast television? Remember those tests they did? At least in the US. Back in the 60s and 70s we'd have tests all the time. "If this were a real emergency..."

But that was broadcast. Truly wireless communications. All you needed was electricity. And if you had a radio with batteries, not even that.

Those days are gone. We are way more vulnerable now in some ways.