why did us fight in vietnam
President Lyndon Johnson supported the Tonkin Gulf Resolution by Congress and began to commit US air and ground forces to fight in South Vietnam. To contain the spread of Communism into Southeast Asia. This was called the domino effect that would have weakened US influence in the Pacific. The USSR was providing arms to North Vietnam. The pretext for directly using US forces was a provocation in the Gulf of Tonkin where the destroyer USS Maddox was attacked by by North Vietnamese patrol boats.