Yesterday’s visit to Iran by Russia’s Foreign Minister is not necessarily bad news in the five-year attempt to persuade Tehran to drop its nuclear ambitions.

Of course, it may be the cementing of an alliance that has been one of Iran’s best tools in keeping sanctions at bay. But the more cheerful interpretation would be that Russia, not keen itself on an Iranian nuclear weapon, is keeping a close eye on the work that Iran insists is merely for electricity.

For all the tension of the past week, as Tehran and Washington spar over new US sanctions, the next event that matters is a report from the International Atomic Energy Agency, the United Nations watchdog. The entire drama, since Iran’s 20-year covert programme was first uncovered, has moved to the rhythm of the regular reports from the IAEA, but if anything could get Russia and China to toughen their stance, the one due in mid-November would be it.

But the most unfortunate development since August is that the IAEA has chosen to become a player in the negotiations. Mohamed ElBaradei, its Director-General, urged the US at the weekend to ease the pressure on Iran. The best bet must be that the next IAEA report will be generous enough in tone to Iran, whatever the practical findings, that it does nothing to bring Russia and China closer to the US.

It is no surprise that Iran’s confidence appears so high. It has a fistful of reasons to be reassured that threats to punish it are flimsy.

The record oil price is one. The recent visit by President Putin (and yesterday’s by Sergei Lavrov) is another. Evidence of China’s similarly valuable support came yesterday, in the rebuff that the Chinese Foreign Ministry gave Tzipi Livni, Israel’s Foreign Minister, when she asked it to support sanctions. No; diplomacy still had far to go, was the answer.

Another strand is the support that President Ahmadinejad received at home after the ungracious introduction he was given at Columbia University, New York, last month; the intended insult backfired, in leaving many Iranians indignant even if they were not supporters of Ahmadinejad.

But the most valuable is perhaps ElBaradei’s own apparent determination to defer the prospect of tighter UN sanctions, evident in August when he struck his own deal with Iran about what it had to reveal to the IAEA.

All the same, the attentiveness with which Iran is following the international debate shows that it is not complacent. A third round of UN sanctions may look a dim prospect at the moment, but there are many signs that the sanctions that the US has imposed on its own are biting. The latest ones aim to deter Europeans from investing in Iran (which US companies are already barred from doing), by curtailing business with three Iranian banks.

At home, Ahmadinejad may have overplayed his hand in demoting Ali Larijani, the chief nuclear negotiator. Protests by critics, including members of parliament, forced Larijani’s reinstatement for the purpose of international talks, albeit under a different title.

Meanwhile, the US presidential candidates are doing a superb job of confusing the world about the US’s future intentions towards Iran after next year’s elections. They have adopted every position on the spectrum between them, although with a bias towards the belligerent.

That keeps Iran worried, and uncertain, a counterweight to its growing confidence.

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