The South Koreans should starve the beast. Pain now, long periods of bliss later. Anyway, most of these materials, if not all, will go to the NORK military.
If they starve North Korea the outcome will be the same as any action we take with the exception of giving aid.
We’ll push Kim into a corner and instead of facing a coup he’ll order the artillery fired, millions in Seoul die, possible nuclear detonation in Seoul or Tokyo, and we’ll flatten North Korea.
That’s the only possible outcome whether we strike first or they do.