At the moment nothing suggests that is likely, as each country continues to try to mobilise the states of the region. The US vice-president, Dick Cheney, has been touring the Arab world, reiterating Washington's determination to prevent Iran from acquiring nuclear weapons. Mahmoud Ahmadinejad, meanwhile, is visiting the UAE, the first by an Iranian leader since independence in 1971 and all the more important because of a serious territorial dispute. Responding to the threatening noises from Cheney, President Ahmadinejad declared: "The US cannot strike Iran. The Iranian people can protect themselves and retaliate."

Although the US administration's current priority is Iraq, it has not given up on Iran. Silently, stealthily, unseen by cameras, the war on Iran has begun. Many sources confirm that the US has increased its aid to armed movements among the ethnic minorities that make up about 40% of Iran's population. ABC News reported in April that the US had secretly assisted the Baluchi group Jund al-Islam (Soldiers of Islam), responsible for a recent attack that killed 20 Revolutionary Guards. According to an American Foundation report, US commandos have operated inside Iran since 2004.

President Bush categorised Iran as part of the "axis of evil" in 2002; the following year he said the US "would not tolerate" an Iranian nuclear weapon. It is worth recalling the context in which these statements were made. Tehran had actively helped the US to overthrow the Taliban. At a meeting in Geneva on May 2 2003 between Javad Zaraf, the Iranian ambassador, and Zalmay Khalilzad, Bush's special envoy to Afghanistan, the Tehran government submitted a proposal for general negotiations on weapons of mass destruction, terrorism and security, and economic cooperation. The Islamic Republic said it was ready to support the Arab peace initiative tabled in 2002 and help to transform Hizbullah into a political party. And in December 2003, Iran became one of the few countries to sign the additional protocol to the non-proliferation treaty, which strengthens the International Atomic Energy Agency's supervisory powers.

However, the US swept all these overtures aside since its only objective is to overthrow the mullahs. To create the conditions for military intervention, it constantly brandishes "the nuclear threat". In 1995 the director of the US arms control and disarmament agency said Iran could have the bomb by 2003; Clinton's defence secretary William Perry predicted 2000, a forecast repeated by Israel's Shimon Peres. Yet last month the IAEA considered that it would be four to six years before Tehran had the capability to produce the bomb.

What is the truth? Since the 1960s, Iran has sought to develop nuclear power in preparation for the post-oil era. Technological developments have made it easier to pass from civil to military applications. Have Tehran's leaders decided to do so? There is no evidence that they have. Is there a risk that they may? Yes, for obvious reasons.

During the Iran-Iraq war, Saddam Hussein used chemical weapons against Iran, but there was no outcry in the US, whose troops are now deployed in Iraq and Afghanistan. Two neighbouring countries, Pakistan and Israel, have nuclear weapons. No Iranian leader could fail to be aware of this situation.

So how is Tehran to be prevented from acquiring nuclear weapons, a move that would start a new arms race in an unstable region and deal a fatal blow to the non-proliferation treaty? Contrary to common assumptions, the main obstacle is not Tehran's determination to enrich uranium. Iran has a right to do so under the non-proliferation treaty but has always said it was prepared to impose voluntary restrictions on that right and to agree to increased IAEA inspections.

The Islamic Republic's fundamental concern lies elsewhere. Witness the agreement signed in 2004 with France, Britain and Germany, in which Iran agreed to suspend enrichment on the understanding that a long-term agreement would "provide firm commitments on security issues". Washington refused to give any such commitments and Iran resumed its programme.

The EU chose to follow Washington's lead. The proposals of the five members of the UN security council and Germany in June 2006 contained no guarantee of non-intervention in Iranian affairs. In response, Tehran suggested "that the western parties who want to participate in the negotiation team announce on behalf of their own and other European countries, to set aside the policy of intimidation, pressure and sanctions".

Without such a commitment escalation is inevitable. Ahmadinejad's election as president in 2005 has not made dialogue any easier, given his taste for provocative statements about the Holocaust and Israel. But Iran is a big country rich in history, and there is more to it than its president. There is much tension within the government, and Ahmadinejad had severe setbacks both in the local elections and in elections to the Assembly of Experts last December. There are substantial challenges, economic and social, and forceful demands for more freedom, especially among women and young people. The only strong card the regime has to win their loyalty is nationalism, a refusal to accept the kind of foreign interference Iran suffered throughout the past century.

Despite the disaster in Iraq, there is no indication that Bush has given up the idea of attacking Iran. The insistence at the weekend by Gordon Brown that there would be no attack on Iran seems unwarranted optimism rather than objective assessment. The idea of an assault against Iran is after all part of the Bushite vision of a "third world war" against "Islamic fascism", an ideological war that can end only in complete victory.

The demonisation of Iran, aggravated by the attitude of its president, is part of this strategy and may well culminate in yet another military venture. That would be a disaster, not only for Iran and the Arab world, but for western, and especially European, relations with the Middle East. Europe's newest leaders - Nicolas Sarkozy and Brown - would do well to remember that.

· Alain Gresh is a specialist on the Middle East for Le Monde Diplomatique, where a longer version of this article appeared

© Le Monde Diplomatique