French war in Indo- China 1947- 54
Between French and Indo Chinese, Americans assisted French as advisors. Vietmihn, a nationalist group surrounded and whipped out French occupying army. At Treaty of Geneva 1954 Indo- China was divided into Laos, Cambodia, North Vietnam and South Vietnam.
Vietcong were communist, support form China and USSR meant fear of communist North taking over South. USA scared that if South Vietnam was taken over by communist North, Laos, Cambodia and others would follow.