The recent rhetoric of the fanatic Iranian president leaves little choice for the Israeli army's general staff. Ten to 15 dispersed key objectives of Iran's "Manhattan Project" must be eliminated before they assemble a nuclear warhead.

In October, 2002, no less an authoritative military expert than Vladimir Putin expressed such a necessity when he told his government:
"If anyone intends to use weapons of mass destruction against our country, we will respond with preventive measures adequate to the threat - wherever there are terrorists, or organizers of the crime, or their ideological or financial sponsors are. I underline, no matter where they are."

Perhaps Ehud Olmert and his colleagues have noted the thoughts of ex-lieutenant-colonel Putin.
This would be a very difficult undertaking for Israel. The destruction of the Iranian nuclear program, some of which is underground, adds up to a far more complex and risky operation than Israel's successful strike on the closer, French-built Iraqi reactor in 1981.

But let us suppose that the IDF can cope with this mission.

THE POLITICAL and military consequences of a nuclear castration of Iran would be extreme. Civilian casualties would be inevitable.
Al-Jazeera, BBC, CNN and RTR would show and tell all of "progressive" humanity about these casualties with hysteria. A new wave of Islamic hatred toward Israel would hardly surprise or distress the Israeli government, but it would be accompanied by destructive military counter-strikes. "Defensive weapons" that Russian governments have provided to Iran and Syria over the past years, including missiles, would rain down on Israel. Some of Israel's nuclear installations could also be hit.

But the alternative to a preventive strike is unacceptable to Israel. Nuclear weapons and the means for their delivery in the hands of the Iranian president, who seems passionate in his desire for the destruction of Israel, cannot be ignored.

An attack on Iran's nuclear program would be the least ugly scenario available to Israel if Iran does not stop, or at least modify, its nuclear program. Undoubtedly Israel would prefer to delay the difficult decision as long as possible, while there is still some hope for a diplomatic solution to the crisis.

AMERICAN POLICY makers understand that a post-strike wave of Islamic terrorism would be directed not only at Israel, but also at the US. This consideration might explain tepid US support for Russia's offer to enrich Iranian reactor-grade uranium on Russian territory.

Acceptance by Iran of this idea - and I think Iran will accept it - will not change anything. It may slow down Iran's program, but it would relieve diplomatic pressure on Iran. At the same time, nothing will prevent Iran from building a parallel uranium enrichment program on its territory.

But the far more controversial decision by Putin's regime - to sell Russia's sophisticated air defense systems to Iran - not only changes the situation in principle but triggers a scenario for possible regional and even global catastrophe.

Israel had room for maneuver for a year and a half, until Iran's probable completion of its first nuclear weapon. Now it has only a few months, because the Russian air defense systems protecting Iranian nuclear objectives will be fully deployed by autumn of 2006. An Israeli strike would be much more difficult, if not impossible, once these systems are in place. This means that a preventive strike by the Israelis would occur most likely before this summer.

Russia's role in advancing the date of this potentially desperate military action by providing Iran with high-quality air defense weapons raises the question of whether Putin might have had some additional purpose besides the profits from his weapons sale. Israel's defensive strike would likely incite Iranian action to block the shipments of oil through the Straits of Hormuz.

Putin seems to perceive such a scenario as beneficial to him.

This week Moscow successfully downgraded of the US attempt to "refer" Iran to the UN Security Council to "informing" that body. This fits perfectly into Moscow's and Teheran's joint strategy of playing for time.

At the beginning of March Iran will "reluctantly" agree to Putin's proposal for Iranian uranium enrichment on Russian territory. The EU, and maybe the US as well, will triumphantly declare a great diplomatic victory. And the nuclear danger from Iran will loom larger than ever.

The writer is Russian security expert, currently a visiting fellow at the Hudson Institute in Washington.