The Cambodian–Vietnamese War was an armed conflict between Democratic Kampuchea, controlled by Pol Pot's Khmer Rouge, and the Socialist Republic of Vietnam. The war began with repeated attacks by the Liberation Army of Kampuchea on the southwestern border of Vietnam, particularly the Ba Chúc massacre which resulted in the deaths of over 3,000 Vietnamese civilians. On 23 December 1978, 10 out of 19 divisions of Khmer Rouge's military divisions opened fire along the shared Southwestern borderline with Vietnam with the goal of invading the Vietnamese provinces of Đồng Tháp, An Giang and Kiên Giang. On 25 December 1978, Vietnam launched a full-scale invasion of Kampuchea, and subsequently occupied the country in 2 weeks and removed the government of the Communist Party of Kampuchea from power. In doing so, Vietnam put an ultimate stop to the Cambodian Genocide, during which 25% of the Cambodian population had already been executed under Pol Pot’s regime.

Phú Quốc is the largest island in Vietnam. Phú Quốc and nearby islands, along with the distant Thổ Chu Islands, are part of Kiên Giang Province as Phú Quốc City. The island has a total area of 589.27 km2 (227.52 sq mi) and a permanent population of approximately 179,480 people in 2020. Located in the Gulf of Thailand, the island city of Phú Quốc includes the island proper and 21 smaller islets. Dương Đông ward, located on the island's west coast, is the island's administrative centre and largest town. The other ward is An Thới on the southern tip of the island.