One official reason: Stopping Communisim. Armchair Generals (Armchair Strategists) have probably 97 other good reasons, but Monday morning quarterbacking is what they do.
Cold war.
The most Americans died in Vietnam which was also the longest war that America was involved in.
Well the main reason was to abolish slavery
The spread of communism into Southeast Asia was opposed to maintain the balance of power.
American history has had many external conflicts. Here are four examples: The Korean War, The Vietnam War, World War I and World War II. These are conflicts that involved the American military.
To fight for their freedom
Part of the cold war.
The United States did get involved in the Vietnam war because of communism in Vietnam.
Kennedy - Johnson - Nixon .
contain communism
The military draft was the real MAIN reason for the protests.
The UK was not involved in the Vietnam war - it was the USA!
US citizens became tired of the war.
They weren't.
Stop communism, preserve the RVN (Republic of South Vietnam).
to prevent communism from spreading in Southeast Asia
Vietnam war
There are far too many to list individually, nor are many of them known.