Well, that’s the question, isn’t it? Here’s Krauthammer:
In U.S.-Soviet deterrence, both sides knew that a nuclear war would destroy them mutually. The mullahs have thought the unthinkable to a different conclusion. They know about the Israeli arsenal. They also know, as Rafsanjani said, that in any exchange Israel would be destroyed instantly and forever, whereas the ummah — the Muslim world of 1.8 billion people whose redemption is the ultimate purpose of the Iranian revolution — would survive damaged but almost entirely intact.
This doesn’t mean that the mullahs will necessarily risk terrible carnage to their country in order to destroy Israel irrevocably. But it does mean that the blithe assurance to the contrary — because the Soviets never struck first — is nonsense. The mullahs have a radically different worldview, a radically different grievance and a radically different calculation of the consequences of nuclear war.
Read the whole thing.