one EMP 200 miles up in the center of the US would take care of those too.
And what about an EMP above China? That technology goes both ways, and our military has significant “hardening” against EMP, and don’t believe for a moment that China isn’t aware of that fact.
China would be a fool to strike out of nowhere, although having a coward CIC like we do now could certainly encourage them, but such a move would start a scenario that has no predicable outcome, IMO.