On 15 January, the Vietnamese reached Sisophon. Pol Pot, Nuon Chea, and Khieu Samphan then moved to Palin on the Thai side of the border, and in late January relocated again, to Tasanh, where Sary joined them. There, on 1 February, they held a Central Committee conference, deciding against Deng's advice about a united front. In the second half of March, the Vietnamese moved to hem in the Khmer Rouge along the Thai border, where many of Pol Pot's troops had crossed into Thailand itself. The Vietnamese advanced on Tasanh, from which the Khmer Rouge leaders had fled only a few hours before it was captured.