The American colonel, troubled by what he was hearing, tried to stall at first. But the declassified record shows he finally told his South Korean counterpart it "would be permitted" to machine-gun 3,500 political prisoners, to keep them from joining approaching enemy forces.

In the early days of the Korean War, other American officers observed, photographed and confidentially reported on such wholesale executions by their South Korean ally, a secretive slaughter believed to have killed 100,000 or more leftists and supposed sympathizers, usually without charge or trial, in a few weeks in mid-1950.

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