If the politicians had turned us loose in Vietnam to wage war...the outcome would have been much different.
I think that's debatable - that the politicians (LBJ/McNamara) interfered outrageously and made it unwinnable I wouldn't argue with, they certainly prolongued the agony. Whether it was ever going to be winnable is another matter, the will of the South to oppose the North following Vietnamisation seems to me to be an important factor in deciding that.