What goals were the United States leaders trying to accomplish in the Vietnam war?

The United States got involved in the armed conflict in Vietnam because it feared a communist takeover of the whole of Vietnam. The Communist Party had established its rule in the North, and in the South, a pro-Western government had been established. Given the French military defeat in 1954 at the hands of the communist guerrilla, the United States got involved progressively in Vietnam. It was a major participant of the Geneva negotiations that sanctioned the division of the country. The American government started by sending some military advisors, until its presence evolved into a full troop deployment in 1965. The US followed the tenets of the containment doctrine and the domino theory.