It was one of the most daring raids of all time and it led to the destruction of Iraq’s early ambitions to acquire a nuclear bomb. In 1981, Israeli aircraft attacked the nuclear testing reactor at Osirak, south of Baghdad, crippling their plant. It was finally destroyed in the Iraq war a decade later when the United States retaliated for the invasion of Kuwait.

Now Israel is preparing for an even more audacious attack on Iran’s nuclear sites at Natanz, near Tehran, Isfahan, and Arak. Israeli pilots, flying F-15I and F-16I fighters, have been practising the long-haul flights and pinpoint manoeuvres that would enable such a mission to succeed. Crucially, the preparations envisage the use of tactical nuclear weapons, the first time such weapons would have been used in warfare since 1945.

How seriously should we take the threat of Israeli action? There is, inevitably, an element of sabre-rattling. Any attack would require, at the very least, Washington’s tacit approval. With George W Bush up to his eyes in Iraq and the Israelis still getting over last year’s humiliation at the hands of Hezbollah in Lebanon, this would seem to be the last thing on American and Israeli minds.

Looked at in another way, however, these events may have made a tactical nuclear strike against Iran more likely. Ehud Olmert, Israel’s prime minister, refused to rule out military action last month, letting slip publicly for the first time the fact that his country has nuclear weapons; surely one of the world’s worst-kept secrets. Like every previous Israeli prime minister, he is committed to preventing Iran from acquiring nuclear weapons. Mahmoud Ahmadinejad, the Iranian president, has called for Israel to be wiped off the map, and has been paymaster to Hezbollah. His willingness to provoke Israel apparently knows no bounds.

That is why this is such a dangerous time. A nuclear-equipped Iran will not meekly join the club of nuclear states content to have the means of defending itself. Iranian-backed terrorist groups, including Hezbollah and Hamas, would have access to dirty bombs, if not full-scale nuclear weapons. There is even a theory that Iran has already acquired some nuclear weapons from parts of the former Soviet Union, to be used against Israel in the event of a strike.

As for America, Mr Bush has privately let it be known that he would be failing in his duty if he left office before the threat from Iran had been contained. With Mr Ahmadinejad thumbing his nose at the world and at United Nations’ inspectors, it is hard to see what the containment strategy is. Sanctions are unlikely to work. The White House could come to welcome Israel’s solution. At the very least, America will find it hard to argue against it.

We can hope that none of this comes to pass, and that a way is found of negotiating Iran down from the nuclear ledge. That may, however, be wishful thinking. As we warned a fortnight ago; containing Iran will be a bigger headache than stabilising Iraq.