War Crimes?
This, from U.S. policy was to shoot Korean refugees, looks pretty damning at first glance:

"If refugees do appear from north of US lines they will receive warning shots, and if they then persist in advancing they will be shot," wrote Ambassador John J. Muccio, in his message to Assistant Secretary of State Dean Rusk.

The background: "Muccio noted in his 1950 letter that U.S. commanders feared disguised North Korean soldiers were infiltrating American lines via refugee columns."

This also must be taken into account:

But William Eckhardt, lead Army prosecutor in the My Lai atrocities case in Vietnam, sensed "angst, great angst" in the letter because officials worried about what might happen. "If a mob doesn't stop when they're coming at you, you fire over their heads and if they still don't stop you fire at them. Standard procedure," he said.