A couple of points:
1) The Iranian regime is totalitarian in character. Thus it requires enemies in the same way that a democratic state needs civil liberties: as a condition of its survival. The regime’s chosen enemies are Israel and the U.S., a.k.a. the Little Satan and the Great Satan. That Obama expected the ayatollahs to tear up their enemies list in exchange for the good opinion of the “world community” shows that where foreign policy is concerned, he is out of touch with reality.
2) Though of course no one can predict the future, it would be dangerous in the extreme to discount the regime’s bloodthirsty rhetoric and assume that having obtained nuclear weapons, it would never use them. I suppose that Obama, who seems to have the backbone of a chocolate éclair, will nevertheless embrace this assumption. But Israel can’t afford to take a chance.