With the quite reliable doctrine of mutually assured destruction, no one is going to use an atomic weapon as an offensive device. Of course they are a powerful defensive fallback position, and nations would be foolish to attack anyone that possesses these weapon. That said, an Iranian nuclear bomb would mean a significant change in the balance of power in the region which is the hidden agenda worry for Israel, USA, Saudi Arabia, and come of the Gulf States. That is a problem which will have to be managed by new and more creative means. Despite all the hysteria about radical Islam in Iran, we should also look to their proud history and culture that extends back over thousands of years. Some of the greatest foreign policy mistakes of the USA is a failure to appreciate the histories and cultures of those on whom they make war.
Clashes between IDF and protesters in Bethlehem and East Jerusalem (Reuters)
from the article: Mossad chief: Nuclear Iran not necessarily existential threat to Israel