Natanz is where the Iranians are carrying out their hectic uranium enrichment programme — something they were politely requested to stop doing by the International Atomic Energy Agency one month ago. The deadline for them to pack up their thousands of centrifuges passed on Friday — but they are still beavering away and have expressed a marked reluctance to take the slightest notice of the international community.

There doesn’t seem to be much doubt that their intention is to produce nuclear weapons; a handful every year, perhaps. The Natanz facility is partially underground, a fact that provoked the IAEA inspectors to note, rather drily, that this was “inconsistent” with the Iranian claims that the plant was solely for the purpose of manufacturing mildly enriched uranium for benignly commercial purposes.

Equally anomalous to this defence is the fact that those same inspectors found particles of extremely enriched uranium at Natanz, the sort of stuff you need to make atomic bombs. Presented with this evidence, the Iranians shuffled their feet a little, looked at the ground and then announced that maybe they hadn’t washed the equipment thoroughly when they bought it from the Pakistanis and consequently there was still the odd bit of weapons-grade material kicking around, sorry about that, you know how it is, can’t get the help, etc.

You can believe them if you wish. It would be a kinder, happier world if we were all able to trust one another. But my suspicion is that Mahmoud Ahmadinejad, Iran’s president, who has expressed a desire to see Israel wiped from the face of the world, may soon have the wherewithal. A suspicion supported with physical evidence and a statement of malevolent intent. What more evidence do you need? An awful lot more, as far as the international community is concerned. Paralysis has descended since the invasion of Iraq and it afflicts not just the United Nations and the European Union but western public opinion, too. So ill-judged and catastrophic was the Anglo-US adventure against Saddam Hussein that it has warped our ability to think rationally about what to do with Iran. Opposition to pre-emptive military action against Iran will be deafening.

The war against Iraq was predicated upon two misconceptions — first of all that Saddam possessed weapons of mass destruction. He did not. His hopeless army possessed scarcely any weapons at all. But even allowing for hindsight, the term “weapons of mass destruction” in Saddam’s case referred only to chemical and biological weapons — which, although thoroughly nasty, are a politically inspired misnomer. It is nukes that inflict genuine mass destruction and there was never a suggestion that Saddam had any of those.

The difference with any action against Iran is stark: hard evidence of genuine WMD in preparation; hard, stated evidence of intent. And a clearly defined, containable and comparatively attainable military objective — knocking out that enrichment site at Natanz.

I have debated this issue with numerous British politicians, from Tony Benn on the left to Steven Norris on the right, and the result is always the same. “We must negotiate with the Iranians,” they all say, a mantra, a form of whistling in the dark.

Well, of course we must first negotiate. Of course we must, later, bring whatever pressure we can to bear from supra-national organisations such as the UN. We should beg, bully, plead and cajole the medieval Ahmadinejad. We should offer economic incentives. When these do not work, we should impose sanctions. We should bar the Iranian team from the World Cup and refuse them entry to the Eurovision song contest — that’ll teach ’em. But what on earth do we do when all that fails, as it looks as though it will? Faced with that probability, there is just silence from the politicians: the question is never answered.

Never mind such niceties as verifying Iran’s nuclear aims: there is still a large tranche of the western world that believes with bovine obduracy that because we and the Americans and the French and the Israelis have nukes, why shouldn’t poor old Third World Iran? Fair play to the burka boys, don’t you think? The answer is simple and yet — in some quarters — quite unsayable: because it is Iran.

There is a final irony: the war against Iraq may have been at least partially responsible for the election next door of a primitive fundamentalist from the Dark Ages. So, too, the commitment within the country to continue enriching uranium, regardless of how unhappy it might make the imperialistic western powers.

One way or another we will need to get to grips with Natanz quite soon. I may not want to live in a world with nuclear weapons — but I really don’t want to live in a world where Iran has nuclear weapons.

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