Rolling Thunder was the HIGHLY restricted bombing of North Vietnam. Hundreds of strategic targets were ignored, ranging from dams to the only Southeastern Asian steelworks(which was then hit for 30 days).
What if there was no Rolling Thunder, and it was a full-blown strategic bombing of the North Vietnamese targets? Dams that provided water for their supplies, their factories, the capitol, their main port, etc. all being hit by the Air Force at "random" times.