F-22 Raptors would kick the crap out of some critical places in the DPRK. Not to mention some other things, airborne, ground and sea based. The rice paddies down in the DMZ north of the MDL would not be the main objective. After eliminating the artillery tubes and tank commands just north of the DMZ, simultaneously Pyongyang would be strategically leveled, and further the Kim's, fleeing, would be smoked to a crisp.
These people are marked people with limited days, and their every move is tracked. Even if underground, WHAMMO!!! they are going to get it with some hitherto unveiled US play-purdies.
I remember seeing some pictures of a military parade in NK ... no planes, few tanks, just men and some artillery ...