mdd:
There is no certainty bombing Iran will get their deep underground nuclear facilities. Especially an air-war only. A ground war will result in significant Allied casualties.
The net result of a war might be an Iran that still has nuclear capabilities. And an Iran that will then rush to complete building nuclear weaponry.
There is also a near certainty that going to any war against Iran will result in Iran engaging in a worldwide terror retaliation.
War is an option but not necessarily the best option.