The US intervened in Vietnam War in 1966.The reason was to put brakes to the advancement of Communist Vietcong,supported by the Communist countries.
The USA got involved in the Vietnam War because Russia had gone in to help The Vietcong (the Communist North). Seeing as the Cold War between Russia and The USA was on at this time, Russia helping the Vietcong was seen as a challenge to the Americans, and they entered the war.
The U.S. Got involved because Communism was rapidly spreading and many people were scared that the U.S. Was going to get a Communist government to if they didn't help to stop the spread.
They got involved because of the government and the government didn't want anyone to find out about secret stuff they did and because the President was scared.
I was there in late 65. The shift was May or June 66. I was gone!!!!
The real answer was power and control, and the Republican could make money, and sing a stupid song in a country that had been fighting for a long time!
It was never they just decided that it was cool so they did it because america don't know squat in the early years haha
Because of the containment policy. The US did not want communism to spread, although they could have gone about it in a different way.