“We have made our choice”, Mohammad Khatami, the President of Iran, asserted at a military parade yesterday, “yes to peaceful nuclear technology, no to atomic weapons.” His venue for that statement reinforces the concern that the intentions of the regime in Tehran are far less benign.

By announcing that it has embarked on a process that will lead to uranium enrichment, and thus the material for an atomic arsenal, Iran has, in effect, said “no” to further co-operation with the International Atomic Energy Agency (IAEA).

Few now doubt that Iran has the facilities and the components to make nuclear weapons if it opted to do so. The constraints on this programme have become political rather than technical. The Iranian authorities agreed last year to permit more aggressive inspection of its nuclear sites. They also signed an additional protocol to the Nuclear Proliferation Treaty to that effect.

Its recent activities have, however, so alarmed the IAEA that its governing body rightly demanded that Iran suspend all activities relating to nuclear enrichment. Still, the Iranian Government has decided to defy the IAEA openly and risk the consequences.

They have done so after making the calculation that the possible consequences will not be very serious. Iran’s original willingness to work with the IAEA was not born of unilateral charity but was the result of explicit political pressure.

The US-led intervention in Iraq concentrated minds in Iran. It was evident that there would be a high price to pay if Iran’s nuclear ambitions were realised. Even the most fanatical sections of the Iranian regime did not want to force a political showdown with the White House. The situation has evolved and Iran has become bolder. The tragic aftermath of the conflict in Iraq has absorbed Washington’s attention. These difficulties have been stoked from and through Iran itself, with hundreds of heavily armed “volunteers” crossing a virtually unpoliceable border every day.

The final stretch of the American presidential contest also makes it harder for Washington to focus on Iran and European nations have realised that Tehran has taken advantage of their willingness to compromise in negotiations.

The regional and international implications of a nuclear Iran are profound and grave. It would be much tougher to deal with an actual nuclear power than an aspiring one. The inner politics of this regime are complex, but to put faith in moderates to act in a responsible fashion has not worked. It is just not clear how much influence they have on the regime or whether, on this issue, they disagree with the hardliners.

It would be far better if the international community resolved to oblige Iran to fall into line with the IAEA. The divide between the United States and the EU on policy towards Tehran has managed to enable the regime there to play one side off against the other. A united and determined stance is what is required for a diplomatic initiative to be anything more than merely wishful thinking.

It is now time for the UN Security Council finally to address this matter and to make it clear what the sanctions will be if the IAEA ultimatum is disregarded. This may well, alas, be the very last chance left to prevent Iran from becoming a dangerous nuclear power.