Who cares? The nukes are a threat to Israel, not the US -- Iranian missiles can't reach the US, and any covert attack would be traced back to Iran using isotope signatures. A nuclear Iran is basically no threat to us, nor to any of our allies. They know that we could flatten Tehran without even using nukes.

(Not that I'd mind them threatening the Saudi oil fields and driving oil up to $250/bbl where it g-d damn belongs. Iran-Saudi war ... yumm ... couldn't happen to two nicer bands of primitive fundies.)