Explain how the presidents of the 1960's influenced policy on vietnam

during the 1960s, United states were involved in a cold war with the soviet union.

At that time, Vietnam was seen as a proxy that could deepen either the soviet union or united states influence in south east Asia.

The president of the 1960s at that time believe that if we did not send our troops there, the soviet union would take control of the rest of the south east Asian countries. This is why majority of them favor the policies to intervene with the Vietnam government,.

i'd assume india mainly because of how isolated japan was.   plus it is a whole china away.