The Air Force rejected adapting to the war in Vietnam as they believed it would be over so they could revert back to focusing on the Soviet Union, they were also embarrassed by the Navy being better prepared. It was a failure, it cost the US an estimated $900 million in return for no real gain. Johnson had stopped Rolling Thunder in order to start peace talks in '69.
Another strategy which wasn't very effective was the bombing of the Ho Chi Minh trails in Laos, titled Operation Barrel Roll, Steel Tiger, and Tiger Hound. Each of these operations concerned different areas of the trails. The campaign against the trails wasn't hugely successful for a few reasons. Although it slightly reduced the transportation of aid into the south it didn't stop it, huge amounts of equipment was still being moved. Upon bombing, the people on the trails would retreat into tunnels to avoid being hit. The Americans also had another aerial intervention in the form of the defoliant Agent Orange in Operation Ranch Hand, 20,000,000 US gallons of it was dropped in total on Vietnam, Cambodia, and Laos. They weren't very effectual, like the bombing of the HCM trails, the VC tended to be in tunnels, instead of hiding in the foliage. .
Search and Destroy was also used, this was very much General Westmoreland's preferred tactic. It involved sending detachments of US troops into villages where they would seek out the VC and then kill them. Shortly afterwards they would leave the village and move onto the next one. There were several disadvantages with using this tactic. The increasing advancement of helicopters meant they were prominently used. However, they created such a noise, that a lot of the time the VC would know the Americans were coming and hide, only to go back into the village once they had gone. Search and Destroy also came with a big civilian cost, roughly 6 Vietnamese citizens were killed for every VC member.
