My Lai's case

At that time there are two sides - one side pro-support Saigon to defend against communism in Hanoi. President Nixon (Republican) supported Saigon from 1963-1972. On the other side who anti-Vietnam war to support the communist Hanoi were, president Johnson, Jean McCan, Henry Kissinger, and John Kerry. The side that anti-Vietnam war at that time used everything that they could to politically attack Nixon to stop supporting Saigon, which led to the victory of the communist Hanoi.