The radius of effect would not be that large from a single nuke and the effect on electronics would not likely be that severe.
We and the Russian detonated hundreds of atmospheric nukes. EMP was noticed but it wasn't a game changer. Yes, a most of our components aren't hardened, but then a lot of them are inadvertently hardened via their location.
And the Norks aren't going to deliver a hydrogen bomb, but a low yield nuke with a low yield EMP.
emp was not a problem then because we didnt explode them over computer chips and delicate electronic devices
the difference in what is manufactured and how is why it is an issue
and I spoke to some former spooks who did frequency analysis for DOD, they are greatly concerned about EMP and think faraday cages are a waste of time for the common man
they recommended going 400 feet underground