WASHINGTON – There are few foreign-policy positions more silly than the assertion without context that “deterrence works.” It is like saying air power works. Well, it worked for Kosovo; it didn’t work over North Vietnam.

It’s like saying city-bombing works. It worked in Japan 1945 (Tokyo through Nagasaki). It didn’t in the London blitz.

The idea that some military technique “works” is meaningless. It depends on the time, the circumstances, the nature of the adversaries. The longbow worked for Henry V. At El Alamein, however, Montgomery chose tanks.

Yet a significant school of American “realists” remains absolutist on deterrence and is increasingly annoyed with those troublesome Israelis who are sowing fear, rattling world markets and risking regional war by threatening a pre-emptive strike to stop Iran from acquiring nuclear weapons. Don’t they understand that their fears are grossly exaggerated? After all, didn’t deterrence work during 40 years of Cold War?

Indeed, a few months ago, columnist Fareed Zakaria made that case by citing me writing in defense of deterrence in the early 1980s at the time of the nuclear freeze movement. And yet now, writes Zakaria, Krauthammer (and others on the right) “has decided that deterrence is a lie.”

Nonsense. What I have decided is that deterring Iran is fundamentally different from deterring the Soviet Union. You could rely on the latter but not on the former.

The reasons are obvious and threefold:

(1) The nature of the regime.

Did the Soviet Union in its 70 years ever deploy a suicide bomber? For Iran, as for other jihadists, suicide bombing is routine. Hence the trail of self-immolation from the 1983 Marine barracks attack in Beirut to the Bulgaria bombing of July 2012. Iran’s clerical regime rules in the name of a fundamentalist religion for whom the hereafter offers the ultimate rewards. For Soviet communists – thoroughly, militantly atheistic – such thinking was an opiate-laced fairy tale.

For all its global aspirations, the Soviet Union was intensely nationalist. The Islamic Republic sees itself as an instrument of its own brand of Shiite millenarianism – the messianic return of the “hidden Imam.”

It’s one thing to live in a state of mutual assured destruction with Stalin or Brezhnev, leaders of a philosophically materialist, historically grounded, deeply here-and-now regime. It’s quite another to be in a situation of mutual destruction with apocalyptic clerics who believe in the imminent advent of the Mahdi, the supremacy of the afterlife and holy war as the ultimate avenue to achieving it.

The classic formulation comes from Tehran’s fellow (and rival Sunni) jihadist al-Qaeda: “You love life and we love death.” Try deterring that.

(2) The nature of the grievance.

The Soviet quarrel with America was ideological. Iran’s quarrel with Israel is existential. The Soviets never proclaimed a desire to annihilate the American people. For Iran, the very existence of a Jewish state on Muslim land is a crime, an abomination, a cancer with which no negotiation, no coexistence, no accommodation is possible.

(3) The nature of the target.

America is a nation of 300 million; Israel, 8 million. America is a continental nation; Israel, a speck on the map, at one point eight miles wide. Israel is a “one bomb country.” Its territory is so tiny, its population so concentrated that, as Iran’s former President Akbar Hashemi Rafsanjani has famously said, “application of an atomic bomb would not leave anything in Israel but the same thing would just produce damages in the Muslim world.” A tiny nuclear arsenal would do the job.

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.

The confident belief that they are like the Soviets is a fantasy. That’s why Israel is contemplating a pre-emptive strike. Israel refuses to trust its very existence to the convenient theories of comfortable analysts living 6,000 miles from its Ground Zero.

© 2012, The Washington Post Writers Group