NK will use min/max artillery approach conventionally to annoy/threaten Seoul with the intent of luring USAF into NK airspace...where NK will pop off an aerial nuke over their own soil (because that is a “defensive” use of a nuke that China won’t spank them for) on the hope that a lucky blast will down a couple of USAF airborne assets which will temporarily cause the USA to stop flying over NK airspace during combat operations.
Likewise, NK will use their rustbucket subs as bait to lure in a USN sub-tracker, where a submerged nuclear mine will be suicide-detonated in the hopes that the blast will sink a U.S. submarine, keeping other USN assets out of NK waters.
In the meantime, NK’s army and civilian population will remain in NK’s vast underground tunnel network for 60 to 90 days, simply letting their entire surface infrastructure be destroyed.
At some point, NK will then send all of its air and army assets Southward while launching all of their ICBM’s in a blitz...hoping to catch the USA during resupply due to expending our munitions the previous 90 days taking out their surface infrastructure.
If they capture Seoul, they will plant a suicide nuke therein and threaten to detonate it if we try to reconquer the city.
Their plan will then call for reparations to be made if we don’t want Seoul destroyed.
...anyway...that’s what you get when you wargame them.