I can understand the concerns regarding a Iranian nuclear warfare capability. Like a tumescent teenager, they would have trouble keeping it zipped up and away and Israel is the target of choice. They are not noted for accepting fools gladly and preemptive strike is a phrase they know well and a concept they have used to great effect.
I do see a possible scenario. The warlike language between POTUS and Iran's HadMyDinner is worked up to something where Israel gets very heated and decides to get their retaliation in first. After a long haul, their bombers inflict serious damage - not total destruction - on Iran's
centrifuge installations. Just enough destruction so that Iran does not have any capability to let the nuclear birds fly loose. America would then tell their puppets they had been very naughty and threaten sanctions in the event of any recurrence. (If the attack is properly planned and successfully executed - there would be no need for Part II) Iran is given a big dose of "Told you so" and offered help in reconstruction of the peaceful application. Any threat of a united Arab reaction to Israel's attack is very small. Possible supporters of Iran are well within range of IDF aircraft.
Reads like something very serious. It would be but exactly the sort of circumstance where preemptive assault is best bet.
If we carry on with threat and counter-threat, Iran will get to the situation where it might be tempted into a bit of this preemptive action.