When Benjamin Netanyahu stood up at the United Nations General Assembly last September with a cartoonish drawing of a bomb designed to show how close Iran was getting nuclear weapons, close observers of Israel’s posture wondered why suddenly Israel had extended the deadline for action against Iran’s nuclear programme.

After all, conventional wisdom expected Israel to strike by October at the latest.

Last week, a clue emerged. Commenting on the recently released quarterly report of the International Atomic Energy Agency, last August, about Iran’s nuclear progress, French Foreign Minister Laurent Fabius concluded that Iran would complete preparations for a bomb in late spring 2013, agreeing with Netanyahu’s newly established time line.

What made Mr Fabius predict with such accuracy an outcome that matched Netanyahu’s predictions?

One answer is the combined and generously shared efforts of Western intelligence communities to gather as much information about Iran’s programme as possible, so as to give policymakers intent on negotiations and sanctions a full sense of the timeline of their efforts – how long we have, when it becomes futile to continue.

Then, this week, Israeli Defence Minister Ehud Barak unpicked more of the mystery to journalists gathered in London. Mr Barak said that the real reason why Israel had not already launched a strike on Iran was that the IAEA’s August report indicated that the regime had set back its nuclear programme by around eight months.

This piece of information was buried in the arcane, technical language of the IAEA report. As a diplomatic source in Vienna, speaking on condition of anonymity, indicated in an email, “Iran has slowed itself down by converting part of the 20 per cent enriched uranium into fuel” but also generally slowed down the pace of enrichment.

Why would Iran do that?

Lest one runs to read readiness to negotiate and goodwill gestures in these actions, Iran is “in a rush to transfer all its centrifuges underground”.

The Iranians must have concluded that, Romney or Obama, and Netanyahu or not, an attack is likely by the late spring.

Why then leave assets vulnerable to attacks, when they can increase the chances of their centrifuges’ survival by moving them to the Fordow facility built under a mountain near Qom? Moving and reinstalling them means they are not busy enriching, which explains the slowing down of production.

Set this aside though and look at the bigger picture – and what one sees is once again an elaborate ruse where Iran enriches just enough uranium at 20 percent for ostensibly civilian purposes in order to prop up its claim that its programme is beyond reproach. Meanwhile, a rush against time has begun to protect Iran’s most invaluable assets – its nuclear technology – from the looming military onslaught.

And if Iran succeeds, continue the diplomatic sources at the IAEA, Iran’s edging close to what Israeli Defence Minister, Ehud Barak calls a ‘zone of immunity’ against Israeli attacks means those attacks may not be able to afford waiting until Spring.

Emanuele Ottolenghi is a Senior Fellow at the Foundation for Defence of Democracies