greater than that of 17 April 1975. For several years, the Vietnamese government sought in vain to establish peaceful relations with the KR regime. But the KR leaders were intent on war. Behind this seeming insanity clearly lay the assumption that China would support the KR militarily in such a conflict. Faced with growing Khmer Rouge belligerence, the Vietnamese leadership decided in early 1978 to support internal resistance to the Pol Pot regime, with the result that the Eastern Zone became a focus of insurrection. War hysteria reached bizarre levels within Democratic Kampuchea. In May 1978, on the eve of So Phim's Eastern Zone uprising, Radio Phnom Penh declared that if each Cambodian soldier killed thirty Vietnamese, only 2 million troops would be needed to eliminate the entire Vietnamese population of 50 million. It appears that the leadership in Phnom Penh was seized with immense territorial ambitions, i.e., to recover Kampuchea Krom, the Mekong Delta region, which they regarded as Khmer territory. Massacres of ethnic Vietnamese and of their sympathizers by the Khmer Rouge intensified in the Eastern Zone after the May revolt. In November, Vorn Vet led an unsuccessful coup d'état. There were now tens of thousands of Cambodian and Vietnamese exiles on Vietnamese territory. On 3 December 1978, Radio Hanoi announced the formation of the Kampuchean United Front for National Salvation (KNUFNS). This was a heterogeneous group of communist and noncommunist exiles who shared an antipathy to the Pol Pot regime and a virtually total dependence on Vietnamese backing and protection. The KNUFNS provided the semblance, if not the reality, of legitimacy for Vietnam's invasion of Democratic Kampuchea and for its subsequent establishment of a satellite regime in Phnom Penh. In the meantime, as 1978 wore on, Cambodian bellicosity in the border areas surpassed Hanoi's threshold of tolerance. Vietnamese policy makers opted for a military solution and, on 22 December, Vietnam launched its offensive with the intent of overthrowing Democratic Kampuchea. A force of 120,000, consisting of combined armor and infantry units with strong artillery support, drove west into the level countryside of Cambodia's southeastern provinces. Together, the Vietnamese army and the National Salvation Front struck at the KR on 25 December. After a seventeen-day campaign, Phnom Penh fell to the advancing Vietnamese on 7 January 1979. Pol Pot and the main leaders initially took refuge near the border with Thailand. After making deals with several governments, they