After several years of border conflict and the flood of refugees fleeing Kampuchea, relations between Kampuchea and Vietnam collapsed by December 1978. On 25 December 1978, the Vietnamese armed forces along with the Kampuchean United Front for National Salvation, an organization founded by Heng Samrin that included many dissatisfied former Khmer Rouge members, invaded Cambodia and captured Phnom Penh on 7 January 1979. Despite a traditional Cambodian fear of Vietnamese domination, defecting Khmer Rouge activists assisted the Vietnamese and with Vietnam's approval became the core of the new People's Republic of Kampuchea. The new government was quickly dismissed by the Khmer Rouge and China as a "puppet government".