富國島
On 1 May 1975 Khmer Rouge forces landed on Phú Quốc which was claimed by Cambodia but controlled by South Vietnam. On 10 May the Khmer Rouge captured the Thổ Chu Islands, where they evacuated and later executed 500 Vietnamese civilians. The PAVN launched a counterattack evicting the Khmer Rouge from Phú Quốc and Thổ Chu and attacked Cambodia's Poulo Wai island.