IOTL, the USA eventually lost the Vietnam War. It lost not because it was defeated militarily but because the war kept dragging on and became a quagmire and lost American domestic support. But most importantly, it lost because it never went all out to win. But what if instead of fighting the war in a limited fashion, the USA wages total war in Vietnam? That is to say, the USA fully mobilizes milliions of troops, invades and occupies North Vietnam and any neighboring countries harboring NVA forces, and fights the enemy using all out brutal and ruthless tactics with little regard for collateral damage or civilians. I'm definitely not saying I endorse this course of action. But it seems to me that if the USA went all out and waged total brutal war, it would win and win overwhelmingly in Vietnam.