It’s impossible to start a humanitarian crisis in North Korea right now. The North Korean people are already eating grass. How much worse could it get for them?
Not our problem. All of North Korea can starve. It is not our job to feed them, or, in a state of war, allow them to be fed.
Besides, no number of North Koreans, military or civilian, is worth the life of a single American.
You can’t win by fighting an enemy’s army (unless that enemy is us - we’re waaaaaaaay too squeamish to absorb real casualties). You have to destroy his logistics. Every army runs on beans, bullets, and bodies. We can’t do anything about Nork bodies, and the manufacture a fair amount of their own bullets. Be we can cut the beans, and we should do so without pity or hesitation. The war will be over that much faster with less loss of life on all sides.