It's called getting your retaliation in first. A flurry of speculation about a possible pre-emptive military attack against Iran began appearing in the Israeli media about ten days ago. Then came reports suggesting the US was making plans for military action and that Britain might allow Tomahawk cruise missiles to be used. Then Israel tested a new long-range missile.

So before the IAEA's new report on Iran has even appeared, the alarmist narrative is well established: the UN watchdog's report will be a "game-changer". Israel's patience is exasperated and it is ready to act alone.

Israel's motives in nurturing a fresh drumbeat of war are understandable. For years there have been Israeli voices arguing that surgical strikes on Iran's enrichment plants would work.

But the argument is flawed. Suppose Iran is hellbent on actually getting the bomb, rather than just making everyone believe it has it. And then suppose the IAEA report has conclusive evidence that Tehran has moved to the point of acquiring weapons and the means to deliver them. Even if the threat was this imminent, the rest of the world would still be insane to let itself sleepwalk into another war just because the hawks in Israel have framed the debate to exclude other options.

Yet, according to a report yesterday in the New York Times, not known for adopting a lenient tone on Iran, the IAEA report is based on at best murky intelligence and, although it will point ominously to a new testing capsule for an "implosion device", will not be conclusive. Which should cast us back to another "game-changing" report: Colin Powell's 2003 presentation to the UN on Saddam's biological weapons.

The best way for Iran's nuclear ambitions to be disarmed, and for Israel's regional security to be enhanced, would be if the hardliners in Tehran were dislodged from power in an Iranian equivalent of the Arab Spring. Yet Western governments continue to turn a blind eye to the sale of technology to Iran that allows it to cripple the opposition. Many of those who have been tortured and jailed since the 2009 elections were hunted down thanks to mobile phone spyware sold by firms like Nokia-Siemens.

Military action would not be quick or surgical; an attack would risk spreading conflict throughout the Middle East, and it would end up strengthening an Islamic regime whose survival is partly built upon the premise of an external threat. If Israel's talk is propaganda, designed to ratchet up pressure for more coherent and effective sanctions in the face of Russian and Chinese opposition, then there is some sense in it. But it is a dangerous game, and one that other Western governments should refuse to play.