REALPOLITIK Trevor Royle

SOMETIMES diplomacy is more about reading the runes than listening to those who have the ear of those in the know. Take the not-so-little matter of a pre-emptive strike to take out Iran's uranium enrichment programme. If you heed the warnings of hawks like John Bolton, former US ambassador to the UN, it's a done deal.

The US or Israel will take appropriate military action during the window of opportunity between the presidential elections in November and the swearing-in of the new president in January 2009. That way, Bush gets what he wants - he is on record as saying that nothing is ruled out to prevent Iran acquiring nuclear weapons - but he will leave the consequences to his successor.

Fortunately, it's not as cut and dried as that. No strike can be mounted if the military is not keen on the idea.

Bush is the commander-in-chief and he gives the ultimate orders, but he also has to listen to the recommendations of the joint chiefs of staff and so far the advice has been cautious. Their chairman, Admiral Mike Mullen, said as much last week when he warned that military action would be a mistake and a better solution could be found through diplomatic channels.

Quite apart from the damage that would be caused by any aerial bombardment, Mullen realises there would be fallout of another kind. Iran would be bound to retaliate and from his charts Mullen can see that the authorities in Tehran would simply close the Straits of Hormuz, a key shipping route.

As it accounts for 40% of the world's seaborne oil trade, the closure would send the market into free-fall and exacerbate the current global economic draw-down.

Of course, the passage would not stay shut for long as the US navy has too much firepower in the Gulf in the shape of the Fifth Fleet. Its commander, Vice-Admiral Kevin Cosgriff, has already fired a shot across Iranian bows by claiming he "will not allow" the Iranians to blockade the vital passage. However, that would involve a naval shooting war with all the risks of further regional entanglement.

At the present juncture, with an unpopular land operation in Iraq, the US public might not warm to the idea of another major and potentially disastrous conflagration in the Middle East.

There is one other scenario no-one should ignore. The Israelis could act unilaterally, or at least with covert US support. They certainly have the motive. Not only has president Mahmoud Ahmadinejad made unpleasant noises about removing Israel from the map, but a nuclear-armed Iran would be a very real threat to regional stability.

During its 60 years of existence, the state of Israel has always obeyed the realistic military rule that it attacks if it feels threatened - just ask Egypt, Syria or Jordan - and there is no shortage of hawks to ram home that message.

When former chief of staff Shaul Mofaz said an attack on Iran is "inevitable" he meant just what he said.

The Israelis also have the capability. In 1981 their air force destroyed a French-built nuclear reactor at Osirik in Iraq and in circumstances that are still far from clear they repeated the dose last year against a similar facility under construction in the Syrian desert.

In both cases the Israelis acted quickly and decisively to destroy a potential threat and, unless the Iranians can prove conclusively their uranium enrichment programme is being developed for civil purposes, trigger fingers will be getting decidedly itchy.

That probably explains why Israel is being remarkably coy about a major exercise that took place at the beginning of June in the skies of the eastern Mediterranean. More than 100 strike aircraft and aerial tankers took part - just the kind of assets that would be used in any attack on Iran.

The optimist in me says that diplomacy will win the day, that as long as Iran remains within the Nuclear Proliferation Treaty they will prefer negotiation to confrontation and will follow the lead given by their foreign minister Manouchehr Mottaki who has discovered "a new sort of atmosphere" in his discussions with Washington.

Perhaps there is, but events can always spring nasty surprises. Twenty years ago the US cruiser Vincennes shot down an Iranian Airbus A300 killing 290 passengers and crew in the mistaken belief the airliner was an attacking F-14 Tomcat warplane.

The subsequent US inquiry exonerated the captain of the Vincennes and dismissed any blame by explaining that the incident happened because the ship's air-warfare co-ordinating officer confused training with reality and fired the ship's missiles in self-defence. Apparently it's a syndrome known as "scenario fulfilment".

But that's precisely what happens when guns are loaded and people get edgy. Let's hope that this time people keep their nerve.