The Bush Administration’s offer to join nuclear talks with Iran is the right move at the right juncture. The conditions that Washington has set — the verifiable suspension of Iran’s uranium enrichment and reprocessing activities and full co-operation with International Atomic Energy Agency inspectors — are not America’s alone. They are exactly the terms laid down by the EU3 of Britain, France and Germany and endorsed by the IAEA board and the UN Security Council.

This is thus an offer that Iran initially refused, but the regime must be aware that to continue to do so would be tantamount to announcing that it has no interest in good-faith negotiations. For months, Iran’s excuse for pulling back from on-off talks, with Russia as well as the EU3, has been that American “hostility” rendered negotiation pointless. That convenient alibi is no longer available. Washington has not only agreed to talk, and explicitly acknowledged Iran’s “right” to civil nuclear energy. It has dangled plums, promising that if Iran proves that it has no intention of acquiring nuclear weapons, the US will “actively support” not only civilian nuclear co-operation, but “progressively greater economic co-operation”. While noting that Iran must abandon support for international terrorism before a wider dialogue could develop, Condoleezza Rice has emphasised President Bush’s desire for a “beneficial relationship” with the Iranian people.

The juiciest plum of all for Tehran is that, after a silence lasting 27 years, even limited direct talks would be a huge domestic boost for the President, Mahmoud Ahmadinejad. He has been clumsily angling for this outcome, most recently in the rambling, ranting missive that he sent to the White House last month. America will be seen to have responded to this repressive rabble-rouser with concessions that it was unwilling to offer his mildly reformist predecessor, President Khatami. That is an unfortunate consequence of a decision which Washington cannot have found easy to reach. If Iran’s now uniformly hardline leadership eventually accepts the offer, Mr Ahmadinejad will trumpet it as a victory for his strategy of confrontation with the West, a sign of Iran’s strength (and the value of nuclear brinksmanship).

There is, moreover, still no guarantee against Iranian cheating, pretending to negotiate while covertly building more centrifuges, fending off for as long as it can the threat of UN sanctions that could, however re- stricted, hurt a regime strapped for cash despite vast oil wealth. Iran still plays a divided field whose key players agree that it must be denied nuclear weapons, but as the agonising over the phrasing of UN resolutions shows, who do not yet agree what to do if Tehran persists in nuclear adventurism. The US has found the right initial pressure point — the Iranian people’s dislike of isolation that most of them associate with an anti-Americanism they do not share, and with years of repression and deepening poverty. The US has inched open the escape hatch; that act puts the regime under pressure to let Iranians emerge.