In July 1973, the Khmer Rouge launched an offensive against Cambodia's capital city, Phnom Penh. Assisted by American air power, the weak Cambodian government repelled the assault and inflicted massive losses against the KR. The timing of the attack made no sense: The U.S. Congress had voted to bar all funding for the war after Aug. 15. In other words, if the KR had waited a month and a half, they could well have taken the city, and certainly avoided the losses. Why didn't they wait?
That tantalizing question lies at the heart of Stephen Morris' fascinating study of the conflict between Vietnam and Cambodia, a clash that culminated in an invasion by Vietnam on Dec. 25, 1978, "the first and only extended war ever fought between two communist regimes."
The offensive was only one in a series of seemingly irrational decisions made by the KR and the Hanoi government during that period. Morris, using material from the Soviet Union's Communist Party Central Committee archives and interviews with leading figures in Cambodia, Vietnam and Russia, provides a disturbing assessment of decision-making by "chiliastic" regimes, those that frame the world in Manichean terms -- such as revolutionary communist parties.