A US shift that could tame Iran's nuclear ambition

It would, said the Iranian negotiator, be tantamount to "trading a lion for a mouse". So much for Tehran's initial response to a US offer of economic assistance in return for curbs on its nuclear programme. As was illustrated so vividly last week in the parliamentary tussle over anti-terrorist measures, however, the fiercest words tend to be exchanged even as a compromise is in the making. And this is the rather more optimistic light in which Iran's latest volleys in the direction of the United States should probably be seen.

It would, said the Iranian negotiator, be tantamount to "trading a lion for a mouse". So much for Tehran's initial response to a US offer of economic assistance in return for curbs on its nuclear programme. As was illustrated so vividly last week in the parliamentary tussle over anti-terrorist measures, however, the fiercest words tend to be exchanged even as a compromise is in the making. And this is the rather more optimistic light in which Iran's latest volleys in the direction of the United States should probably be seen.

The likelihood is that Tehran was thoroughly wrong-footed by one of the more deft diplomatic U-turns to have been executed by the US administration in recent years. At the weekend, the Secretary of State, Condoleezza Rice, announced out of the blue that the US would put its weight behind European diplomatic efforts to resolve the US-Iran nuclear dispute. The offer was this: if Iran abandoned its uranium enrichment programme, the US would lift its long-standing objections to Iranian membership of the World Trade Organisation and remove its block on Tehran obtaining parts for commercial aircraft.

The change of heart was excellent news for British, French and German negotiators. Their fear has long been that US belligerence towards Iran posed almost as great a threat to their efforts as Iranian stubbornness. An almost equal concern was that, unless they were underwritten by the US, their efforts would lack the necessary clout to push Iran to comply.

By yesterday, the tone of Iran's response, now set by President Khatami, had become more conciliatory. While there was, he said, no question of Iran giving up its nuclear fuel programme altogether, it was prepared to "work with the world" to give more assurances that Iran was not moving towards building nuclear weapons. The moratorium on uranium enrichment remains in force.

US officials stressed that stronger action would be needed if Iran still refused to meet its international obligations. But the atmosphere has changed. We may not be watching the endgame in this dangerous dispute, but this may be the skirmishing that heralds the beginning of the end.