Vietnamese refugees fleeing Vietnam, 1984 On 2 July 1976, North and South Vietnam were merged to form the Socialist Republic of Vietnam.[308] Following the communist takeover, 1–2.5[309] million South Vietnamese were sent to reeducation camps, with an estimated 165,000 prisoners dying.[310] Between 100,000[309][311][312] and 200,000[313] South Vietnamese were executed.[314] R.J. Rummel, an analyst of political killings, estimated that about 50,000 South Vietnamese deported to "New Economic Zones" died performing hard labor,[278] out of the 1 million that were sent.[309] 200,000 to 400,000 Vietnamese boat people died at sea, according to the United Nations High Commissioner for Refugees.[315] Phnom Penh, the capital of Cambodia, fell to followers of the Communist Party of Kampuchea, commonly known as the Khmer Rouge, on 17 April 1975. Under the leadership of Pol Pot, the Khmer Rouge would eventually kill 1–3 million Cambodians in the killing fields, out of a population of around 8 million.[21][22][23][316] At least 1,386,734 victims of execution have been counted in mass graves, while demographic analysis suggests that the policies of the regime caused between 1.7 and 2.5 million excess deaths altogether (including disease and starvation).[316] After repeated border clashes in 1978, Vietnam invaded Democratic Kampuchea (Cambodia) and ousted the Khmer Rouge in the Cambodian–Vietnamese War. The Vietnamese installed a new government led by Khmer Rouge defectors, which killed tens of thousands and enslaved hundreds of thousands.[317] In response, China invaded Vietnam in 1979. The two countries fought a brief border war, known as the Sino-Vietnamese War. From 1978 to 1979, some 450,000 ethnic Chinese left Vietnam by boat as refugees or were expelled across the land border with China.[318] The communist Pathet Lao overthrew the royalist government of Laos in December 1975, establishing the Lao People's Democratic Republic.[319] The conflict between Hmong rebels and the Pathet Lao continued in isolated pockets. The government of Laos has been accused of committing genocide against the Hmong,[320][321] with up to 100,000 killed out of a population of 400,000.[322][323] From 1975 to 1996, the United States resettled some 250,000 Lao refugees from Thailand, including 130,000 Hmong.[324] More than 3 million people fled from Vietnam, Laos, and Cambodia, many as "boat people". Most Asian countries were unwilling to accept refugees.[325] Since 1975, an estimated 1.4 million refugees from Vietnam and other Southeast Asian countries have been resettled to the United States,[326] while Canada, Australia, and France resettled over 500,000.[327] In 1988, Vietnam suffered a famine that afflicted millions.[328] Vietnam played a role in Asia similar to Cuba's in Latin America: it supported local revolutionary groups and was a headquarters for Soviet-style communism.