Why in HELL would a person do this?

Just because you have personal demons, it's not a good enough reason to put your country in a touchy international situation with a bunch of fanatics with nuclear weapons and the largest army in the region. He could have gone to South Korea if he felt a need to visit old places.

If he was one of the Marines surrounded at the Chosin Resevoir when China entered the war, it wasn't quite the same as "fighting behind enemy lines" means in WWII context. It was the front line, and it was moving as the Marines advanced in the opposite direction...as they like to describe it.

We should have stayed out of Korea in 1951, and he should have stayed out now.