I do not believe that tiny North Korea is a threat to the United States any more than other countries that it has invaded and/or bombed back to the Stone Age.
Kim’s regime might be paranoid but they are not suicidal and any response, such as the one described below, will be a direct response to US (and allies’) aggression.
REPORT: N KOREA ‘SPACE NUKE’ PROGRAM GREATER THREAT THAN ICBMS
US largely defenseless to EMP attack from space
Launched from a satellite, a small nuclear warhead only needs to explode 300 miles above the Earth to knock out a power grid – and the US is largely defenseless to such an EMP attack North Korea could potentially deliver.