Could be a possibility. That’s what happened in the Jericho series.
In any case, I don’t think the country is going to be susceptible to an invasion and occupation,
because an EMP doesn’t do anything to get rid of the 100’s of millions of privately owned firearms. This is what foreign powers fear more about our country than our military - occupation-wise.
The absence of mention of America as a factor in end-times prophecy certainly means that we’ll be a non-factor when the time comes.
We may have 100s of millions of firearms, but months later in the aftermath of a successful EMP attack - who is going to man them effectively?
An EMP attack has the potential of causing the death of 100s of millions of Americans through social chaos, disease, and starvation. IIRC, the estimated mortality rate after a year amy approach 90% in affected areas as we almost instantaneously devolve into the 18th century. But 70% or 80% mortality would leave us nearly as vulnerable to foreign enemies who are well armed, well fed, healthy, and have the advantage of technology mobility on their side, would it not?