Seriously, other than their navy of Zodiacs with machine guns, does Iran posess a significant threat via air, missle and land based capabilities? Would we need to occupy Iranian territory on the easter side of the Straits of Hormuz?
Iran has a significant anti-shipping capability. They armed with silkworm missles as well as possibly up to 20 modern missle cruisers and 1000s of light attack craft. Anti-shipping missles are very hard to counter. We would have to spend a considerable amount of time using air and land assests to clear the coastal batteries and Iranian Naval vessels out. I would say if this scenario went into effect, the Straits could be shutdown for at least 3 -5 weeks. This would have a major impact on oil shipments (rougly 1/6) of the world's oil is exported through the strait.
However, what is the alternative? A nuclear-armed terrrorists country who has already shown its disdain for the west and publicly stated intentions of "wiping Israel off the map."