Iran’s contempt was demonstrated yesterday when it officially inaugurated a “new phase” in its heavy water production plant despite the opposition of the security council and the International Atomic Energy Agency, the world’s nuclear inspectorate. According to a reliable report, an Iranian official said the plant has been operational for a month. Similar plants have been used by India, Israel, Pakistan and North Korea to turn uranium into plutonium for bombs.

Clearly, although the Iranians claim a sovereign right to “peaceful” nuclear power, the IAEA has not reported its suspicions about them to the security council without good reason. We can only hope that Tehran has overreached itself. This is a game of high stakes in which the outcome is far from certain. At some point America or Israel could decide that the danger was so great that a military attack was the only option left. The Iranian bomb is still thought to be five years away, however, so a strike seems remote at present.

Iran and Mahmoud Ahmadinejad, its unpredictable president, may calculate that they can exploit the disunity of the security council and use old friends such as China and Russia to sidestep any sanctions. They may well be correct. Sergei Ivanov, the Russian defence minister, has signalled that Moscow would not support sanctions. John Bolton, America’s ambassador to the UN, talks of imposing them through a “coalition of the willing”. But who is willing and would the sanctions work? Shimon Peres, the Israeli deputy prime minister, seems to believe that Iran would cave in under pressure. But it is hard to see how Iran feels motivated to back down given its oil resources and the disunity of the security council. The United States appears to have no real plan. President Bush has let the Europeans lead the way in seeking a diplomatic solution just as Tony Blair and Jacques Chirac are on their way out. France has again shown Europe’s weakness with its vacillation over sending troops to Lebanon.

The West is faced with a nation seemingly determined to get nuclear weapons. Few doubt that an Iranian bomb would lead to a nuclear arms race across the Middle East. At the same time diplomacy is floundering and sanctions seem remote, although not as remote as a military strike that has a high risk of failure and a certainty of uniting the country at a time when its youth seemed more inclined to embrace western values. It is 27 years since the West lost Iran to newborn Islamist forces. These Muslim revolutionaries have transformed international politics and the West is still struggling to deal with them. This would be farcical if it were not so fraught with danger.