TGWATY is one hundred percent right.
To use an old joke, the problem with Vietnam was that it was full of Vietnamese.
The war was lost. The battles were won. To claim that the war weas lost because of military errors is to entirely miss the point, really. The decision not to invade North Vietnam, or the decision to deploy tanks, or the decision to do this or that or the other thing, all those points are basically irrelevant. The U.S. armed forced outperformed the NVA and the VC by a huge, huge margin. Making it a huger margin would not have caused the war to be won.
To win a war, you must have a specific objective that must be won:
Gulf War 1.0 - Kick Iraq out of Kuwait
Gulf War 2.0 - Conquer Iraq
World War II- Conquer Germany and Japan
Korean War - Kick North Korea out of South Korea
Civil War - Conquer the Confederacy
If the specific objective is winnable, then the war is winnable. The Vietnam War, very simply, did not have a specific and winnable objective. The war was originally sold as defending South Vietnam from North Vietnam. Truth be told, however, the South Vietnamese government was (after a few US-supported shenanigans) not really a government at all, but was rather a puppet pseudo-government of a foreign empire (the United States) with all the legitimacy and public support you would expect of such a government (none at all.) So the USA was in the untenable position of defending South Vietnam from the South Vietnamese. In other words, they were trying to “save” a people from conquest by, in part, the people they were saving. It was a Mobius strip situation.
With all due respect to my American friends, the truth of the matter was that the Vietnam War degenerated to the point that, basically, the United States was fighting a war in order to further the occupation and subjugation of Vietnam. Granted, that was because they were afraid of Communism, but from the Vietnamese perspective the Americans were simply the inheritors of the French mantle of occupation, who in turn had loaned it out to the Japanese. That many not have been the original intent of Kennedy and Johnson, but by 1970 that was the practical situation. A boiled frog error, as it were The only way the United States could have forced Vietnam to accept occupation, as has been pointed out, would have been to kill all the Vietnamese. Of course, then the USA would have won nothing at all anyway.
Realistically there is no scenario you could envision that would have resulted in a U.S. win, no matter what you let the military do. Invade North Vietnam? You’d just have to occupy the entire country in the face of fierce resistance, probably resulting in eventual withdrawal and humiliation. Nuke it? You’d start a nuclear war. Send more troops? How would that help when the exisitng troops were kicking asses and taking names anyway?
The U.S., as I suggested in another thread, lost the Vietnam War for exactly the same reason Great Britain lost the American Revolution. In fact, the two wars bear a great many similarities.