There is also the troubling question of the massacres in Cambodia, in which the numbers of dead and disappeared were only equalled by Hitler and Stalin.
Yes, we made many an error in VietNam. Chief among them was our refusal to fight to a finish and win, based on what turned out to be a faulty assumption that this would lead to intervention by China and Russia. The quarter-century between Korea and VietNam did not, in that regard teach us much.
But it did teach our enemies ... actual and potential ... that we no longer had the guts for military solutions to military problems. It also taught our enemies that our policies could be manipulated by an alliance between them and our media.
What's truly at stake for us now..?
The Jihadists want to replace our U.S. Constitution with Islamic Law, our President with an Islamic Mulah in the White House.
It's hardly a coincidence that the modern age of terrorism began with the US withdrawal from Vietnam. Once it was learned that you didn't need to be able to defeat a major power on the battlefield - just in the media - the hijackings and truck bombings began.