John Thomson: Time is short, but a deal can be done

The West must deal directly with the Supreme Leader to convince him that Iran's 30-year-old regime needs no nuclear weapons

Is the stand-off between Iran and the West critical? Yes. Are we at a make-or-break point? Probably. Is Britain relevant? Questionably.

Britain and the other Europeans were important when we were hanging on to George Bush's coat-tails to prevent him from attacking Iran (or from getting a nuclear weapon). But we followed the US line with such enthusiasm that, now that Obama has replaced Bush, we find ourselves, together with France, to the right of Washington; strange for a Labour government.

The five-plus-one (the five permanent members of the UN Security Council plus Germany) are about to hold high-level policy discussions. The Anglo-French political directors will continue, it appears, to insist on "suspension", meaning Iran halts its nuclear programme in exchange for the five-plus-one ceasing to ratchet up sanctions. Obama has dropped "suspension" as a condition for negotiations, doubting that it can stop Iran seeking nuclear weapons. Were we to persuade the new US team to stick with "suspension", we might well wreck the best chance of a negotiated settlement. The Supreme Leader, Ali Khamenei, is congenitally anti-American. It will not take much to convince him that talk of change is a smokescreen. Once done, it will be hard to undo.

Time, as the five-plus-one privately admit, is against us. So are the facts. We have slipped into denying reality. The Iranians, as they have repeatedly said, are not going to "suspend". Worse, Iran has "mastered" the technology of centrifuge enrichment, something we and the Israelis used to describe as our "red line". We pretend that Iran has not already produced enough low-enriched uranium to make one bomb were they to enrich it further to "weapons grade". Russia and China refuse to support tough sanctions. Iran has seen off unanimous Security Council resolutions. In short, our policy has failed and, if we persist with it, the failure will grow.

Is there an alternative that will prevent Iran from having nuclear weapons? Yes, and Britain, hitherto so often an object of Iranian suspicion, could be the catalyst to make it work. Back in 2006, we insisted that the US join the negotiations, basically because we understood that there had to be an accommodation between the two main protagonists. Now we must promote that accommodation by facilitating US-Iranian talks. We should open a line to the Supreme Leader – we know how to do that – and say that if he is serious about resolving the crisis in a mutually acceptable way, so are we. We should reassure him that we do not seek the end of his regime – 30 years after it began is as good a time as any to do so – and acknowledge that there will be senior people who will shun any accommodation; we should aim at a Security Council resolution blessing, whatever mutually acceptable accommodation is reached, raising sanctions and sending the nuclear issue back from the Council to the International Atomic Energy Agency (IAEA) for continued monitoring.

The nuclear issue needs to be resolved quickly, but a real accommodation involves more. This is something both sides agree upon and we should outline a practical way of giving effect to it. We should propose to Tehran and to our colleagues in the five-plus-one that if the Iranians will discuss the proposals made by the five-plus-one in June 2008, we will discuss the Iranian proposals of May 2008. It would be impractical to consider all these ideas simultaneously, so we should suggest taking one political security item that appears in each proposal, say Iraq and Afghanistan, and one economic/energy item that both support, say Middle East energy resources and their distribution, and add to these the nuclear problem. That would probably give us an acceptable initial agenda, which could be used first in confidential bilateral US-Iran discussions and, if they prosper, in talks involving all the five-plus-one members.

We should urge the Americans to say to the Iranians that they have noted repeated statements by the Iranian President and Foreign Minister favouring an international consortium to enrich uranium in Iran. But these have been brief and lacking in detail. How seriously are they to be taken? Would the Iranians please elucidate? We should stress to our partners that time has favoured, and is continuing to favour, the virtually unconstrained and increasingly successful development of the Iranian enrichment programme. By comparison with the continuance of this situation, an international consortium, albeit enriching on Iranian soil, is preferable. An independent national enrichment facility leaves all decisions up to Iran and involves precious little international oversight. It would be easy to establish secret enrichment facilities and hard to detect them. By contrast, IAEA safeguards accompanying an international consortium, together with the daily operational involvement of international managers and technicians, is as effective a deterrent to secret enriching and bomb-making as can be devised.

Would the Iranians accept? We shall not know until we try, but several considerations suggest they would. They would achieve international respectability, an end to sanctions, Security Council approval, the return of the nuclear file to the IAEA. And they would achieve their bottom line: enrichment on Iranian soil. They would get the financial and technical help with their reactor programme which they have publicly sought.

Finally, this solution avoids provoking other Middle Eastern states into beginning the development of nuclear weapons.

Mr Miliband, if you want accommodation in the Middle East and no nuclear weapons in Iran, this is a deal you cannot afford to miss.

Sir John Thomson, a former UK permanent representative at the UN, is currently a research affiliate at MIT