Although none of us are enamored with North Korea, there was a fair share of atrocities that were committed by UN forces on the NK population and the South Korean government against communist sympathizers in their own country. The Wiki article goes into it in some detail. (No, it doesn't make it OK because "they were doing it".)
(As an aside, I sometimes bitterly contemplate how many great Korean minds were lost in that war because of their personal politics)
War is still war, there were deaths, veterans who weren't the same, etc etc. I'm a child of the 80s, so I can't say I remember the details, but war isn't always a pretty thing. Going by what Wikipedia says (yes, I know it's a single source), the US wasn't exactly smart about how it was handled leading up to the Korean war.
After all, they have nothing to hide...