The attempt to talk Iran down from its nuclear ambitions is going badly. Yesterday Tehran formally told the International Atomic Energy Agency, the UN watchdog, that it would move farther ahead with its uranium enrichment, taking it one big step closer to nuclear weapons capability. That contradicts a statement last week purporting to be ready for a deal — one of a long series of such feints.

The parallel front of diplomacy is faring poorly. The six countries actively involved in talks to dissuade Iran from its course — the US, Britain, France, Germany, Russia and China — have not even agreed to take the matter to the UN Security Council. They cannot agree because of China’s reluctance to back new sanctions against one of its main trading partners, and the frosty state of relations between China and the US. Beijing might, if pressed, express outright opposition to such talks, the US fears, although some French officials are more hopeful that a deal might be done. But not quickly. Nor is the European Union likely to edge ahead of the UN and put together its own sanctions; it is more likely that the US will repeat its past success in going alone.

The Foreign and Commonwealth Office called on Iran yesterday to move away from “contradictory rhetoric”, a polite phrase for the stalling and lying that has characterised Iran’s recent statements. On Sunday Iran declared its intention to enrich uranium to 20 per cent; a long step towards converting the material from the level needed for reactor fuel towards that needed for weapons.

It claims that it would use this enriched uranium in the Tehran research reactor — but this does not make sense because Iran lacks the technology to make the material into fuel rods. The move merely adds to suspicions that it has no plausible civilian purpose for central aspects of its programme.

The one strand of hope comes from the persistence of the Iranian opposition after the fraudulent election, despite the execution of some of those who took part. Protests are planned this week on the anniversary of the Revolution.

No one can safely assume that a new government would jettison Iran’s nuclear work — the object of pride even for many opposed to the regime — but it might be more willing to talk. That is why, in trying to design new sanctions, effort is rightly being expended trying to shield ordinary Iranians from the worst effects.

In the end, however, that will be impossible if the sanctions are to bite.

The sanctions track is not dead but it is moving painfully slowly, even by the standards of past talks. Iran’s statements are wild and contradictory; the response from diplomacy needs to be steady and plausible. At the moment it is neither.

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