IS IT all part of a carefully calibrated campaign of bluff and rumour intended to support tightening sanctions and bring Iran to the negotiating table, or is the ground really being prepared for an attack on Iranian nuclear facilities in the next few months? Perhaps it is neither and the people who count, yet to make up their minds, are frantically hedging and debating.

In early February the annual Herzliya security conference in Israel provided a platform for the country's military and intelligence elite to air their concerns about Iran's progress toward a nuclear weapon. Israel's hawkish defence minister, Ehud Barak, said that the “window” for an effective strike was rapidly closing because the continuing movement of essential uranium-enriching centrifuges to the Fordow underground facility, close to the holy city of Qom, would give Iran a “zone of immunity” in which it could construct a bomb regardless of any intervention by the outside world.

Attacking the case for waiting to assess the impact of the latest round of sanctions, due to come into effect by midyear, Mr Barak warned that “whoever says ‘later' may find that later is too late.” He added that “the assessment of many experts…is that the result of avoiding action will certainly be a nuclear Iran, and dealing with a nuclear Iran will be more complicated, more dangerous and more costly in lives and money than stopping it.”

Mr Barak's American opposite number, Leon Panetta, who was travelling with journalists to a meeting with his NATO counterparts in Brussels, confided soon afterwards that there was a strong likelihood of Israel attacking Iran in April, May or June, when the skies are usually clear. Mr Panetta was not speaking on the record, but later turned down an opportunity to disown his remarks.

Iran's supreme leader, Ayatollah Ali Khamenei, responded by using his nationally broadcast Friday sermon on February 3rd to commit the country to continuing its nuclear programme no matter what, and to threaten both Israel and America. He described Israel as a “cancerous tumour” that “will be removed” and declared that if war broke out “it would be ten times deadlier for the Americans” than for Iran.

Mr Khamenei also called on regional allies to attack Israel. “Iran would assist any country or organisation that would fight the Zionist regime, which is now weaker than ever,” he said. It is a call that may, however, fall on deaf ears. Iran's main ally in the region, the Syrian government, has other things on its mind. If it falls, pro-Iranian groups in Lebanon and Gaza will find their supply-lines cut.

Amid the escalating war of words, the military preparations for a conflict are indeed under way. The head of ground forces at the Iranian Revolutionary Guard has announced exercises in the south of the country, near the Strait of Hormuz, and America has begun its largest amphibious-landing drill for a decade, described by Admiral John Harvey of the US Fleet Forces Command as “informed by recent history” and “applicable” to the Strait of Hormuz. Meanwhile, DEBKAfile, an excitable but at times well-informed Israeli security website, reported that “many thousands” of American troops have arrived at two islands close to the Strait, Masirah in Oman and Socotra in Yemen.

Yet for all the alarums and excursions, there are few hard conclusions to draw about whether an attack on Iran is imminent, or whether Israel is prepared to act unilaterally. And it is not clear whether, if it was convinced this was about to happen, America would feel compelled to hold Israel back and carry out the strikes itself. Only Israel's senior leadership (and perhaps the Americans) know whether the Israeli air force is capable of carrying out an effective attack on its own.

Attempting to calm things down, Barack Obama said on February 5th that he did not think Israel had “made a decision on what they need to do” and that the two countries would work in “lockstep as we proceed to solve this, hopefully diplomatically”. Mr Obama will be mindful that an attack would dominate his bid for re-election in November—though it is unclear whether he would gain as a war president or lose ground because of a surge in oil prices and an economic reversal.

The consequences might not be as catastrophic as some fear. On the other hand they fall into the disturbing category that Donald Rumsfeld, a former American defence secretary, once called “known unknowns”. Unfortunately for Mr Obama the decision is more likely to rest with Mr Barak and his prime minister, Binyamin Netanyahu, than with him.