1970: the US invaded Cambodia, a country it was already bombing in hapless pursuit of North Vietnamese forces. The invasion had the unintended consequence of unleashing Cambodia's Khmer Rouge, a communist force previously under the disciplined rule of North Vietnam. It's genocidal leader, Pol Pot, soon launched his own equally disastrous version of China's Cultural Revolution., After US troops left, the Vietnamese finally routed the Khmer Rouge in 1979. Under its reign, entire harvests had been destroyed, a 5th of Cambodians had perished, and famine had struck. Nearly a million Cambodian refugees, many starving, were either in Thailand or packed into refugee camps along its border.-Countdown by Weisman.