Don't know much about the Vietnam War, do you?
But yes, there is certainly only so far the application of military force will achieve, it is but one arm of the action.
Not like they were using Laos and Cambodia (where we couldnt follow officially due to the ROE) to move troops and munitions from North Vietnam and China. Also not like their headquarters and training facilities were in Cambodia. Clearly also werent fighting the NVA, just the VC.
Vietnam, technically, was a military success for the US, but a dismal political failure. The actual bodycounts (which is how we were guaging how the war was going), were in our favor, as were most of our military engagements. They simply did the right thing, didnt give up, waited us out - our own populous turned on the war, demanded it end, and we pulled out. They lost most of the battles, but won the war. We'd go in and take an objective, kill everyone there - only to clear out and let the NVA take it back over.
The way the Vietnam war was ran, was a massive clusterfuck.