The problem with IF N. Korea does respond is that they do not have to settle for short range nukes aimed at the west coast. Those surveillance submarines spotted off the east coast recently ought to wake people up. They can nuke the east coast, any major city from a submarine, or they could do a multi prong attack, then what? [and yes I KNOW they were NOT N. Korean subs that were seen recently, doesn't matter, do you think N. Korea does not have any submarines roaming around?]

Nobody seems to have considered that.

True, most people do focus on their work towards a land-fired nuclear armed ICBM. However, they have test fired missiles from subs before. I trust (or hope) the US military apparatus is well aware North Korea's naval fleet and their potential or lack there-of.