Israel has two basic choices. It can sit and wait, hoping the Iranians do not drop a bomb on Tel Aviv; or it can preemptively attack, hoping to destroy, or at least retard, the Iranians' nuclear capacity.

American foreign policy "realists" tend to favor the first option. At the core of their argument is the idea that Israel has nuclear weapons and can therefore rely on Mutually Assured Destruction (MAD) just as the U.S. did during the Cold War. Does Iranian President Mahmoud Ahmadinejad say he wants to wipe Israel off the map? It's probably just rhetoric. After all, he knows that if he tried, Israel would retaliate, turning Tehran into a parking lot.

This may seem realistic in Washington or Cambridge, but not in Tel Aviv. Israel is a small, crowded country with a very poor civil defense infrastructure and a population traumatized by its own recent history. Perhaps the Iranian government doubts that the Holocaust happened, but there are 6 million Israeli Jews (that population figure is a macabre coincidence) who don't doubt it. For Israelis, "never again" is more than a phrase over a museum gate.

It is possible, even likely, that Israel could survive an Iranian nuclear attack physically - but not psychologically. It is doubtful that Israel could carry on as a sane, not to mention democratic, society. This is the great insight of Ahmadinejad.

An Israel assaulted in this way would react, of course. But it might not react in the predictable, proportionate, tit-for-tat fashion that the realists have laid out.