Australia, New Zealand and the US were bound together through the ANZUS Pact which provided for mutual support in the Pacific and Asia.
The americans didnt like the Lai Massacre which involved unarmed civillians in Vietnam getting killed by American soldiers The number of american soldiers getting killed was growing which made them doubt their leadership Some americans didnt agree with the reasons the leadership used to justify the war with
to stop the sprend of communism
The U.S. wanted to stop the spread of communism.
The spread of communism into Southeast Asia was opposed to maintain the balance of power.
The U.S got involved in The Korean war and Vietnam for many reasons. The U.S got involved in the Korean War because the United Nations called upon all member countries to help support South Korea. The United States had a relationship and treaties with South Vietnam so when the North attacked it was our duty to honor our relationship.
Various reasons. If you go by American involvement in Vietnam, the dates will be different than the entire war itself. There was also a matter of secrecy as to just how long the US had been involved in Vietnam. For example, the first Special Forces soldier to die in Vietnam (Captain Harry Cramer, 1SFG) was killed in October of 1957, and his name was left off of the Vietnam Wall when it was unveiled in 1982, because the US government did not want to make it publicly known just how early on they had been involved in Vietnam.
After the Vietnam war the Soviet Union did not attack or overtly support the expansion of Communism through military means. No war stopped as such but Communist agression was forever checked. Stopping the Communist expansion was one of the USA's reasons to get involved in Vietnam and some argue that the war was successful due to this.
Communist infiltration into South Vietnam.
to fight communism
Vietnam did not hate the Khmer Rouge. The main reasons that Vietnam sent troops to help defeating the Rouge are considered of 2 reasons: 1/ Vietnamese troops will loot resources from area that they travel by. 2/ Cambodia is Vietnam's close neighbour, and the Khmer might attack the borders of Vietnam.
Ignorance...
Businesses influence the political environment abroad By getting the government involved. Government is involved in international business for many reasons, including tariffs and controlling unemployment.