Not quite impunity. USA may support Israeli action.
I anticipate that Israel, with USA supplied refueling, will drop the largest "bunker-buster" bombs that F-15s can carry in their specially adapted bomb racks on the Iranian nulcear facilities. These bombs may weigh as much as 10 tons each, one to a plane. These bombs are designed to penetrate much reinforced concrete. If the attack is really well planned, it will include bombs targeted at the Iranian political leadership as well, but I doubt it.