"While U.S.intervention aimed to build a strong state that would provide a bulwark against communism after U.S. withdrawal, bombing instead weakened local government and non-communist civic society. Moving from no to sample mean bombing reduced the probability that the village committee positions were filled by 21 percentage points and reduced the probability that the local government collected taxes by 25 percentage points. The village committee was responsible for providing public goods. Bombing also decreased access to primary school by 16 percentage points and reduced participation in civic organizations by 13 percentage points."In other words; bombing the living shit out of people pisses them off and makes them LESS likely to go along with whatever cunning plans you have for winning their hearts and minds, or grabbing their balls, for that matter.
How well this study conflates with the current enthusiasm for various Western polities' for bombing the shit out of the Middle East is difficult to assess. But it certainly does seem to suggest that John Paul Vann may or may not have been right about the best weapon for suppressing rebellions but he seems to have been absolutely correct about the WORST.