Was it right for the United States to enter the Vietnam War?

The answer to this question is a matter of opinion. So I will discuss the reasons people supported and opposed the war. 

Those who supported the war viewed Vietnam as another front in the Cold War. They thought that if the spread of communism was not resisted, that it might spread throughout Southeast Asia and even to places like India and Indonesia like, according to a theory of the time, "dominoes." They thought the United...

The answer to this question is a matter of opinion. So I will discuss the reasons people supported and opposed the war. 

Those who supported the war viewed Vietnam as another front in the Cold War. They thought that if the spread of communism was not resisted, that it might spread throughout Southeast Asia and even to places like India and Indonesia like, according to a theory of the time, "dominoes." They thought the United States had a moral obligation to support the people of South Vietnam, who were in danger of having a Communist regime imposed on them by the North and by the Vietcong. Even most opponents of the war would have admitted that if the United States simply stood on the sidelines, South Vietnam would inevitably fall to communism. Even after the fact, some people argue that American intervention in Vietnam slowed the spread of communism by demonstrating American resolve to fight against it.

Opponents of the war tended to argue that the United States had no business intervening, especially militarily, in the affairs of countries on the other side of the planet. To them, the war was an example of American imperialism, not altruism or even wise Cold War strategy. Others argued that without a full-scale intervention, the war in Vietnam would not be successful. Still others, especially after the fact, pointed out that while North Vietnam was communist, the war in the region was best understood as a nationalist conflict that was aimed as much at establishing a Vietnamese nation as at spreading Communism around the world. It was not part of a global Communist plot, and this way of thinking led many way planners to underestimate the commitment of the North Vietnamese and the Vietcong as well as the support for the VC in South Vietnam.