The Killing Fields were quite visceral and difficult emotionally. The worst part for me was when they played the music and diesel generator noise used to mask the screams of those being murdered from the ears of the other prisoners who had no idea they would soon be killed too. They were the last sounds that the victims ever heard. I already knew the basic story of the Khmer Rouge regime, but when I learned that the U.S., U.K, U.N., etc. all recognized the Khmer Rouge as the legitimate government of Cambodia after they had been overthrown by the Vietnamese, I was shocked. I guess it's an example of the questionable maxim that the enemy of my enemy is my friend and shows how the all-consuming fear of communism inhibited better judgment.