When governments undertake grand gestures in the full glare of public attention, the only thing you can be sure of is that they do not mean what they appear to mean. That's a useful rule of thumb to apply to any exercise in public diplomacy but it's especially helpful when trying to fathom the volatile politics of the Middle East.

There has been a certain choreographed quality to events in the skies over the eastern Mediterranean and the Gulf in the last month. This week Iran fired a volley of medium-range missiles into the skies over the Gulf, demonstrating its capacity to hit targets in Israel. A month ago, Israeli warplanes carried out large and fearsome warplane exercises over the Mediterranean that looked like a practice run for a bombing raid on Iranian nuclear facilities.

It's clear what we are supposed to think. Israel is sufficiently agitated now by the Iranian nuclear threat that it is in the military-strike-planning stage, flying sorties that match in range precisely the distance between Israeli air bases and Tehran. Iran in response makes clear it has the missile capability to take out Tel Aviv and Jerusalem.

But appearances can be deceptive. In Iran's case at least part of the deception has already been exposed - to mildly comical effect. It turns out that the picture of the launch of four Iranian missiles that appeared on the front pages of newspapers around the world yesterday was itself a fake.

If you look carefully at the picture, you'll notice that the missile second from right has clearly been pasted in - its launch contrail is identical to that of the one to the left and the cloud of desert sand in its wake is identical to that on the right. Original copies of the photo have now established that the fourth missile failed to fire and so, to cover up the embarrassment, and presumably to protect the promotion prospects of some hapless officer in the Revolutionary Guards, a fairly crude construct was sent to foreign news agencies.

Bad news: clearly some of the most sophisticated and effective Western technology has fallen into Iranian hands after all. Good news: it's Photoshop.

But if the Iranian military's efforts to deceive are cruder, they may be no less opaque than the cloud of smoke around Israel's own superficially plausible warning shot.

The simple reality is that, for all its sabre-rattling, Israel cannot carry out an attack on Iran's nuclear facilities on its own. An Israeli strike would require the active co-operation of the US. Israeli F15 and F16 warplanes would not only have to fly and be refuelled in Iraqi airspace - controlled by the Americans - but the whole operation would require logistical support from US bases on the ground in Iraq. Support helicopters would need to be based in Iraq and rescue teams needed to evacuate any downed Israeli pilots would have to operate inside Iraq.

In short this would be in effect a joint US-Israeli mission. The catch is that Washington has no intention of joining in any attack any time soon.

The military leadership is opposed. Last week Admiral Michael Mullen, the Chairman of the Joint Chiefs of Staff, said that an Israeli strike would open up a “third front” for the US - after Iraq and Afghanistan - and suggested it could break an already stretched military.

The political leadership at the Pentagon is opposed. Robert Gates, the Defence Secretary, rarely misses an opportunity to caution in private about the risk associated with an attack on Iran. His senior aides are focused hard on building on the improving stability in Iraq - something that has been achieved at least in part with some covert co-operation between the pro-US Iraqi Government and the Iranians.

The Treasury is opposed. Hank Paulson, the Treasury Secretary, not only fears the damage to the US economy and markets that a strike would have as the price of oil rose to at least $200 per barrel. There is also growing optimism at the Treasury that the financial sanctions that it is co-ordinating against the Iranian regime are starting to bear fruit. Though German companies unscrupulously continue to shop around for business in Tehran, officials say, other European companies are increasing co-operating. This week's decision by Total, the French oil giant, to pull out of a possible investment in Iran is seen as a signal victory.

And of course the State Department is opposed. Cynics might suppose this is because it's always opposed to anything that might involve someone getting hurt, but that would be unfair. Condoleezza Rice and her colleagues are genuinely confident that they have toughened European resolve and that their diplomacy is working.

It is, of course, possible that George Bush would defy his Secretary of State, Treasury Secretary, Defence Secretary and the entire leadership of the US military and order US participation in an Israeli mission.

One theory, popular in the office of the Vice-President, Dick Cheney, is that the US will have a narrow window to support an Israeli attack. A strike before November's election would be politically disastrous because of surging oil prices and intensified wars in Iraq and Afghanistan. But if Barack Obama wins, they fear his public commitment to intensified diplomacy with Iran would mean any chance of stopping the nuclear programme would be lost. So, they argue, the US would need to co-ordinate an Israeli attack between November 5, the day after the election, and January 20, when a possible Obama presidency begins.

But this brings us back to the latest round of choreography. If you're going to do it, why signal to the Iranians months in advance? When Israel brilliantly took out Iraq's nuclear reactor at Osirak in 1981, it did so without any warning at all.

In any case, the jaundiced Cheney view of the willingness of an Obama administration to address the Iranian threat may not be justified. There is a surprising amount of continuity in US foreign policy. Mr Obama is already backing off some of his more dovish commitments as the general election nears. Don't be surprised if he turns out to be as unready to accept a nuclear-armed Iran as any Republican.

So this current round of sabre-rattling is probably just, to paraphrase Clausewitz, diplomacy by other means, reminiscent of the scary game of bluff and counter-bluff we all played in the Cold War.

But it's worth remembering that the West only won the Cold War when it demonstrated forcefully that it was prepared to do what was necessary to stop the other side from annihilating it, even at the risk of massive damage to itself. We're not there yet, and the Iranians may still need convincing that the West has that kind of resolve today.