That is a very particular arrangement of the facts, that really doesn't have the shape of truth to it. Vietnam was a former French colony conquered by the Japanese WW2, that wanted to restore their independence.The Allies liberated South Vietnam, restoring French colonial rule and seeking to reconquer the whole nation. It was deeply unpopular with the people. Moreover the South wanted to conquer the north with French support and US financing, they fought to a stalemate and an uneasy peace.

Who violated the ceasefire under what circumstances is contested, but ultimately does not really matter - neither side wanted peace, and the hostilities would've resumed anyway one way or another.

The end result was that the US antagonized a people who were fighting for their own freedom, and found itself in an unwinnable war - creating an allied (or at least independent) country from a people you bombed to the stone age is an impossible task.

From this follows that no, the US military wasn't just another dozen bombed out villages away from final victory, when it was backstabbed by those peaceniks at home.

An ounce of diplomacy at the right place and time would've been the best for both the United States and Vietnam, and would've netted them everything they wanted on top of international goodwill.