US forces sent to prop up totally artificial "republic" in the south of Vietnam; helped Ngo Dinh Diem fake elections and suppress the population until he tried to cram Catholicism down throats of the Buddhist majority. Killed during coup d'etat 3 weeks before Kennedy assassinated. Military junta ran South Vietnam until it was defeated by the People's Army of Vietnam (PAVN). The US military referred to the PAVN as the North Vietnamese Army (NVA), and resistence in South Vietnam itself as "Viet Cong."
In Cambodia, war crept across the border as a result of Ho Chi Minh Trail; ruler, Norodim Sihanouk, tried to contain it through negotiation but in 1970 overthrown by a CIA coup; military junta totally useless and Khmer Communist Party formed an alliance with supporters of the monarchy (GRUNK). Named "Khmer Rouge" by Sihanouk before 1970.
In Laos, pitted Pathet Lao (Communist) against Royal Lao Army. RLA extremely poor, and Western assistance was much less than that of Communist Vietnam. Heavy US bombing there & in Cambodia.
The collapse of South Vietnam in early '75 allowed a total rout of the anti-Communist forces in Indochina.
Laos, tragically, remains horribly affected by huge numbers of unexploded mines.