what if the Administration in the United States in power during the early 1960's decides that for whatever reason South Vietnam is not worth the trouble it presents and does not send military aid in any form, including advisors during this period and withdraws or ceases the aid already being given.
With the United States not involved I would assume this would also cause a lower amount of involvement by the USSR and China in aiding North Vietnam and the Vietcong. If that were the case, would South Vietnam be able to hold its own against the North?