Iran deal renews question: Was this war necessary?

It is perhaps the most fundamental question of the Iran war. If the goal of the war was to prevent Iran from acquiring a nuclear weapon, and if the U.S. attack of June 21, 2025, either obliterated or substantially damaged Iran’s nuclear facilities, and if additional targeted bombing could have finished the job of destroying those facilities, why was it necessary for the U.S., along with ally Israel, to go to full-scale war against Iran at the end of February 2026, targeting a broad range of targets, assassinating the country’s supreme leader as well as other key figures and setting off further war and an economic debacle that may or may not be resolved by the current peace negotiations?