Vietnam War
The United States began to send military advisors to help train and support the South Vietnamese Army. It was fighting against the Viet Cong, also known as the National Liberation Front, a communist party based in South Vietnam that was controlled with North Vietnam. The Viet Cong began a campaign of assassination in 1957. In 1959, North Vietnam dramatically increased its military assistance to the Viet Cong, which then began attacking South Vietnamese military units. Because of domino theory, the US feared that if communism took hold in Vietnam, it would then spread to other countries nearby.