Well it started as a police action, and actually I believe was called that until it ended.
America sent in "advisers" to consult with the south Vietnamese and their army. This was part of the cold war, and the main motivation was to try and stop the communist influence coming from the north. Over the course of 5 years after they arrived things did not go well. Then combat troops started to arrive.
Three reasons would be
#1 Stop communism
#2 Display our military power
#3 Help the Vietnamese people (although this one is flimsy at best)
America sent in "advisers" to consult with the south Vietnamese and their army. This was part of the cold war, and the main motivation was to try and stop the communist influence coming from the north. Over the course of 5 years after they arrived things did not go well. Then combat troops started to arrive.
Three reasons would be
#1 Stop communism
#2 Display our military power
#3 Help the Vietnamese people (although this one is flimsy at best)