from elements of the Vietnam People's Air Force, crossed the border along several axes with the objective of forcing the Kampuchean Government to negotiate. On the battlefield, the KRA quickly lost ground to the Vietnamese. By the end of December 1977, Vietnam had won a clear military victory over Kampuchea, as Vietnamese formations marched through Svay Rieng Province and only stopped short of entering the provincial capital. Despite the ferocity of the Vietnamese retaliation, the Kampuchean Government remained defiant. On 31 December 1977, Khieu Sampham declared that the Kampuchean Government would "temporarily" sever diplomatic relations with Vietnam until the Vietnamese military withdrew from the "sacred territory of Democratic Kampuchea". On 6 January 1978, PAVN divisions were only from Phnom Penh, but the Vietnamese Government decided to withdraw its forces from Kampuchea because they had failed to achieve Vietnam's political objective. During the withdrawal, the PAVN also evacuated thousands of prisoners and civilian refugees, including future leader Hun Sen. 1978: preparations for regime change Instead of being sobered by the Vietnamese show of force, the Kampuchean government boasted that the Vietnamese withdrawal was a major victory for Democratic Kampuchea, comparing it to the "defeat of U.S. imperialism" on 17 April 1975. The Kampucheans went on further to proclaim that "our 6 January victory over the annexationist, Vietnamese aggressor enemy has given all of us greater confidence in the forces of our people and nation, in our Kampuchean Communist Party and our Kampuchean Revolutionary Army, and in our Party's line of people's war". The Kampuchean leadership claimed that one Kampuchean soldier was equal to 30 Vietnamese soldiers, so if Kampuchea could raise two million soldiers from a population of eight million, it could wipe out Vietnam's population of 50 million and still have six million people left. In reality, Kampuchean leaders simply ignored the condition of the population in their own country and Vietnam; the Vietnamese, though poor, were in good physical condition, while Kampuchea's population was physically and mentally exhausted from years of hard labour, starvation and disease. In addition to the disparity in population, there was also a great disparity between the fighting capabilities of the armed forces of the two countries. In 1977, Vietnam was estimated to have 615,000 soldiers and 900 tanks, supported by a 12,000-member air force with 300 combat aircraft, including one squadron of light bombers. In comparison, Kampuchea had an army of 70,000, only a