Why didn't the united states intervene in the Khmer Rouge genocide

Answer:The UN is largely controlled by Western powers. Because of the length and impact of the Vietnam war in the US, many of those in the West grew weary of issues in Asia. When unverified reports of death came out of Cambodia, the West was aware of it, but was war fatigued, so the issues were largely ignored.

pol pot's complete control of communications leaving the country ensured a long delay in the world having a real understanding of what was going on.

I think Syria this past year is a good comparison. If mass genocide took place in the Middle East, and it was not totally clear what was going on, you better believe the president of the US as well as other foreign entities would get flack for wanting to intervene. We had video in Syria and we still hesitated. That is the biggest danger of unnecessary war, the inevitable public apathy that could enable truly horrific things