Vietnam is in Vietnam, it has not moved. It is a physical place.If you mean to ask Why have Vietnamese people come to the United States, please click on that.
France (Apex)
Before the American used to think with their technology and firepower, they would protect the world from the communist. The Vietnam war proved that they were wrong.
US Military Advisers were in South Vietnam to help the South defend themselves. When that didn't work, US Regulars were sent in. When that didn't work, they vacated the field.
Escalated the Vietnam War from a guerrilla war into a conventional war against North Vietnam.
To contain communism also to protect American ideals and broaden our influence in other counties
In reference to Vietnam: Congress agreed ot allow our troops to defend themselves and help protect South Vietnam from the spread of Communism, but they did not declare war upon North Vietnam.
The US never invaded Vietnam.
South Vietnam was considered an ally of the US.
The US helped South Vietnam with the South's blessing; the North was deciding if they should fight just the Southerners, or the US too. In the end, the North fought them both.
US Military personnel were in Vietnam from 1955 thru 1975.
See: Vietnam