On the day the doctrine was declared, an agreement was signed that granted oil majors Exxon and Mobil a stake in Aramco, previously exclusively owned by their US counterparts Chevron and Texaco. Securing Saudi oil was the cornerstone of the Truman Doctrine in the Middle East.

Washington hoped fear of communism would rally the region behind its cause. It didn't for two main reasons: first, the pressure for Middle East political change owed more to domestic factors than communist subversion; second, the November 1947 UN General Assembly vote to partition Palestine. It led to the creation of Israel, the first Arab-Israel war and the mass expulsion of Palestinian civilians. The US' Middle East Truman partners, Israel and Saudi Arabia, were to be enemies in 1956, 1967 and 1973 and still have not made peace.

The obsession with communism was ultimately counterproductive. Washington failed to spot the Afghan civil war that provoked Soviet intervention in 1979 and the Iranian revolution the same year were signs of the new challenge of Islamic radicalism. And since the collapse of the Soviet Union in December 1991, the US has lacked a guiding principle for its Middle East policy.

President Bush in January started to fill the vacuum. His new approach involves containing Iran. This could be a watershed development. 'The Holy Grail of US Middle East policy has always been the hope of persuading Arab and Israeli allies to agree on a common enemy and thereby relegate their mutual hostilities to a subordinate role,' Columbia University professor Gary Sick wrote in an essay published on the Gulf 2000 website in January. 'Trying to get the Arabs to conclude that the Soviet Union was a more immediate threat than Israel was always a losing proposition, though it did not prevent several US administrations from trying. But Iran, as a large, neighbouring, non-Arab, radical Shia state, may fulfil that role more convincingly.'

But will the new containment doctrine work? At its heart is a contradiction between Iranian nationalism and Shia Islam. The Shia are a Muslim community with a distinct political culture and a powerful religious hierarchy. But they are divided by belief, practice, language and borders. Most Iraqis are Shia who, like the majority in Iran, follow the line of succession to the 12th Shia Imam. But they have their own leaders and do not follow without question the rulings of Iranian clerics. Iranian national identity owes much to its pre-Islamic Persian inheritance.

Washington will have to decide what matters most: countering Shia radicalism or preventing Iranian hegemony. It would be wrong to regard Shiacommunities outside Iran as fifth columnists for the Islamic republic. The political priority for the Middle East is emancipating minorities, not demonising them. Addressing Shia grievances and tolerating their traditions will do more to reduce Iranian influence than pouring further weapons into a region that already has more than enough.

Iran is the Gulf's most populous nation with interests that deserve recognition. Goods, money and people have been flowing across the lower Gulf for more than 2,000 years. This pattern cannot be reversed by a State of the Union speech.

The US, the world's largest energy importer, has a legitimate interest in the region. But it has no right to dictate. Western Europe's enthusiasm for everything American after 1945 is absent from the Middle East in 2007. The US public, willing foot-soldiers in the war against communism, are tiring of Gulf adventures that produce no measurable results.

Delivering a just and comprehensive