But even zealots and despots have a powerful instinct for self-preservation, which Iran's leaders have exhibited many times -- as in the war with Iraq, which they agreed to end after Iraqi missiles started landing in Tehran. The Iranians know that any use of nuclear weapons traceable to them would be sure to accomplish one thing: their annihilation.
That prospect was sufficient to deter Josef Stalin and Mao Zedong, both of whom were once regarded as madmen bent on world domination. Even fanatical regimes don't take actions they know will be fatal.
Nor would the bomb help Iran in pushing its neighbors around. More likely, it would push them even closer together in opposition to Tehran -- and even closer to the United States. We, after all, have a bigger military than Iran's and a lot more nukes.
The only real value of acquiring an atomic arsenal is to deter attack and invasion. Iran was designated part of the Axis of Evil by President George W. Bush. One other member, Iraq, lacked nukes and was invaded by the U.S. Another, North Korea, had them and wasn't. Iran didn't miss the lesson there.
In the event that sanctions fail to dissuade Tehran from going nuclear, war is no answer. A better response would be for the U.S. to inform Iran that any use of nuclear weapons against anyone will elicit a response in kind. If our nuclear guarantee protected Europe against the Soviet arsenal, it can protect our friends in the Middle East.
As long as the viper is holed up, though, we would be wise not to crawl in after it. Even if you cut off a snake's head, it may still bite.