Iran issued dramatic threats to the US yesterday about the consequences of an American or Israeli military attack on its nuclear plants, part of the past week’s showy verbal exchanges with the US and the European Union. But the real drama lies in the next stage of complicated negotiations, hard to interpret even by the intricate standards of the six-year wrangle over Iran’s nuclear aspirations.

Their unpredictability stems from new factors: disagreements within Iran on whether to negotiate, and on what terms; the dwindling possibility of military action by the US or Israel, now very unlikely; and the Bush Administration’s new interest in links with ordinary Iranians, to build on the pro-American feeling within the country.

“The Zionist regime is pressuring White House officials to attack Iran”, said Ali Shirazi, a mid-level cleric, who is Supreme Leader Ayatollah Ali Khamenei’s representative to the Revolutionary Guards. “If they commit such a stupidity, Tel Aviv and US shipping in the Persian Gulf will be Iran's first targets.” That rhetoric follows reports in the US media of Israeli air force exercises, which stirred speculation about a strike on Iran's nuclear facilities.

There are reasons to see this symmetrical eruption of threat as mainly posturing, on either side. It is hard to find even hawks in Washington who are keen on airstrikes, given the difficulty of the mission, the uncontrollable effects on the region and the opposition from the American public, Congress, much of the US military and allies of the US. Nor is an Israeli strike possible without US backing, given that it would have to send aircraft or missiles over Iraq. Some Western officials agree wryly with yesterday’s remark by Mahmoud Ahmadinejad, the Iranian President, that for Bush, a strike would be “political suicide”. There have even been signs from the US of a very different tack. Officials considered sending consular staff to the US section within the Swiss Embassy in Tehran, according to Mark Fitzpatrick of the IISS think-tank in London, to help Iranians to get visas and take advantage of pro-American feeling in Iran. But a senior adviser to Ahmadinejad blocked it, Fitzpatrick said.

The real drama now centres on Iran’s response to an offer of economic rewards put forward by the “E3 plus 3” - diplomatic slang for Britain, France, Germany, the US, Russia and China, in return for its agreement to suspend uranium enrichment. Senior Iranian officials suggested last week that Iran might look favorably on the offer. There was talk about a “freeze for freeze” - Iran not adding enrichment capability, in return for no more sanctions. But the response “said nothing about suspension or freeze for freeze”, one Western official who has seen the letter said, adding that it was largely a justification of the Iranian position. Yet the text did not rule out negotiations either, and Javier Solana, the EU’s representative, will meet the Iranians, probably within days, to ask what they really mean.

What Iran wants, Western officials believe, is to buy time while waiting for a new US president, and keeping enrichment going. If that is right, Solana will not get far, and the E3 plus 3 will return to trying to find sanctions that Russia and China would support, while both sides wait for the result of the US elections.

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