Define "advanced". Are you talking US or Russian "advanced" or "advanced" for NK?
To generate an EMP that will cover the US, you need at least 1 MT at 250 miles. For US "advanced", you need the ability to loft over a ton. Early (1950's) H-bombs were about 12 tons.
I’m going to assume there are Russians assisting the Norks.
And an EMP blast over the entire US would be overkill if the goal is to eliminate our ability to project a military presence overseas to any large extent.
Even IF our military is hardened against such an attack, how willing are our services going to be if they know their families are in great peril in CONUS?