Chieh moved 33,000+ Republic of China Army soldiers mostly from Hunan Province to Vietnam and they were stationed at Phu Quoc. Later, the army moved to Taiwan in June 1953. There is currently a small island in Kaohsiung, Taiwan's Chengcing Lake that was constructed in November 1955 and named Phu Quoc Island in memory of the Nationalist Chinese loyal soldiers who was detained from 1949-1953.
During the Vietnam War the island housed South Vietnam's largest prisoner camp (40,000 in 1973).
In 1967, during the period when Cambodia was under Sangkum control, the country's ruler, Norodom Sihanouk, aimed to make the border internationally recognized; in particular, in 1967, the North Vietnamese government recognize theses borders. As written in an article from Kambudja magazine in 1968 (and quoted in the Sihanouk website), entitled "border questions", this border definition recognize that Phu Quoc island is in Vietnamese territory, even if Cambodian claims were made later.
On May 1, 1975, a squad of Khmer Rouge soldiers raided and took Phu Quoc Island, but Vietnam soon recaptured it. This was to be the first of a series of incursions and counter-incursions that would escalate to the Cambodian–Vietnamese War in 1979
