Source: The TelegraphAdrian Blomfield
Israel has refused to reassure President Barack Obama that it would warn him 
  in advance of any pre-emptive strike on Iran's nuclear capabilities, raising 
  fears that it may be planning a go-it-alone attack as early as next summer. 
The US leader was rebuffed last month when he demanded private guarantees that 
  no strike would go ahead without White House notification, suggesting Israel 
  no longer plans to "seek Washington's permission", sources 
  said. The disclosure, made by insiders briefed on a top-secret meeting 
  between America's most senior defence chief and Benjamin Netanyahu, Israel's 
  hawkish prime minister, comes amid concerns that Iran's continuing progress 
  towards nuclear weapons capability means the Jewish state has all but lost 
  hope for a diplomatic solution.
On Tuesday, UN weapons inspectors released their most damning report to date 
  into Iran's nuclear activities, 
  saying for the first time that the Islamic republic appeared to be building 
  a nuclear weapon. It was with that grave possiblity in mind that 
  Leon Panetta, the US defence secretary, flew into Israel last month on what 
  was ostensibly a routine trip.
Officially, his brief was restricted to the Middle East peace process, but the 
  most important part of his mission was a private meeting with Mr Netanyahu 
  and the defence minister, Ehud Barak. Once all but a handful of trusted 
  staff had left the room, Mr Panetta conveyed an urgent message from Barack 
  Obama. The president, Mr Panetta said, wanted an unshakable guarantee that 
  Israel would not carry out a unilateral military strike against Iran's 
  nuclear installations without first seeking Washington's clearance.
The two Israelis were notably evasive in their response, according to sources 
  both in Israel and the United States.
"They did not suggest that military action was being planned or was 
  imminent, but neither did they give any assurances that Israel would first 
  seek Washington's permission, or even inform the White House in advance that 
  a mission was underway," one said. 
Alarmed by Mr Netanyahu's noncommittal response, Mr Obama reportedly ordered 
  the US intelligence services to step up monitoring of Israel to glean clues 
  of its intentions. 
What those intentions might be remains distinctly murky. Over the past 
  fortnight, Israel's press has given every impression that the country is on 
  a war footing, with numerous claims that Mr Netanyahu and Mr Barak are 
  lobbying the cabinet to support the military option.
Two weeks ago Israel tested a long-range ballistic missile capable of reaching 
  Iran, its first since 2008. Shortly before, the Israeli airforce took part 
  in Nato exercises in Sardinia that involved air-to-air refuelling, a key 
  component of an aerial strike on Iran. A separate exercise in and around Tel 
  Aviv tested civilian readiness in the event of a missile strike against the 
  city. In a sign of the febrility of the public mood, many beach-goers 
  apparently mistook the air raid sirens for a genuine Iranian attack and fled 
  in panic for their cars. There were similar jitters in Iran yesterday, when 
  a huge but apparently accidental explosion at arms dump outside Tehran 
  killed at least 27 soldiers and shook the city.
Speculation about an imminent Israeli military action has been a regular 
  occurrence over the years, but rarely as fevered as now. Last week, a 
  British official even suggested that an attack could come before Christmas. 
Few in Israel believe that is likely and the difficulty of mounting an 
  operation over winter, when cloud cover hampers aircraft targeting systems, 
  means that if military action is being considered it will not come before 
  the spring or summer of next year. 
Many observers also believe that the bellicose rhetoric voiced by a number of 
  senior Israeli figures in recent days is largely bluff, designed to goad the 
  international community into imposing sanctions of such severity that Iran 
  would be forced into economic ruin if it persisted with its nuclear 
  ambitions. Israel says that if Iran's central bank were sanctioned and a ban 
  on Iranian oil exports enforced by an international naval blockade, military 
  action would not be necessary. 
Mr. Obama has already publicly stated that he does not believe the West can 
  overcome Russian and Chinese opposition to the sanctions Israel wants, 
  leaving military action increasingly as the only alternative. 
Mr Netanyahu may have another reason to bluff. In recent months, Meir Dagan, 
  who retired as director of Mossad at the beginning of the year, has made a 
  series of unprecedented speeches countenancing against Israeli military 
  action - describing it as "the stupidest idea I've ever heard". 
His comments have infuriated the Israeli establishment - senior officials have 
  said they would like to see him behind bars - because they fear it could 
  convince Iran's Mullahs that Israel's sporadic talk of war is a fiction. 
Hints by Mr Netanyahu that he is considering the military option may be 
  designed to resurrect Iran's paranoia of Israel, something seen in the 
  Jewish state as a powerful deterrent, says Yossi Melman, a leading 
  intelligence analyst and journalist. 
"Meir Dagan made a laughing stock of military action," Mr Melman 
  said. "Netanyahu believes he damaged the deterrent and he wants to 
  repair it." 
Yet the fact that Mr Dagan chose to speak out - extraordinary in itself for a 
  just-retired Mossad chief - suggests that he believes Mr Netanyahu is intent 
  on attacking Iran. 
Tellingly, until last year, Israel's four most powerful military and security 
  chiefs, including Mr Dagan, were all strongly opposed to military action. 
  All four have now been replaced by younger men who may be less able to stand 
  up to Mr Netanyahu, not that Israeli prime ministers are necessarily bound 
  to heed objections from their top military advisers anyway. In 1981, 
  Menachem Begin did just that when he bombed Iraq's nuclear reactor at 
  Osirak. 
If Israel is to attack Iran, many in the country believe time is running out. 
  Last week's report by the International Atomic Energy Agency (IAEA) 
  highlighted Iran's apparent determination to build a nuclear warhead, but 
  did not indicate how long it might take. 
Some in Israel, however, believe it is very close. 
"It is my personal opinion that, if the Iranian regime decides to do so, 
  it can produce a nuclear explosive device within a year, plus or minus a few 
  months," said Ephraim Asculai, a former IAEA official and leading 
  Israeli expert on Iran's nuclear programme. 
Not everyone agrees. Some argue that a covert espionage operation has caused 
  such delays that Iran still needs another three years to build a bomb. 
  Sabotage efforts by Israeli, American and British intelligence have 
  successfully slowed Iranian progress, most notably via the Stuxnet computer 
  virus that caused the centrifuges at Iran's Natanz uranium enrichment plant 
  to explode. Mossad agents on motorbikes are also believed to have planted 
  magnetic explosives on the cars of at least two key Iranian nuclear 
  scientists as they weaved through Tehran's traffic jams. Mohsen Fakhrizadeh, 
  the scientist and Revolutionary Guards officer who is thought to be the 
  ultimate mastermind of the nuclear programme, is now believed to be under 
  round-the-clock protection as a result. But, whatever the time frame, some 
  in Israel believe there is additional cause for urgency that could prompt 
  military action sooner rather than later. 
According to western intelligence assessments, Tehran is preparing to move the 
  bulk of its nuclear production to a plant beneath a mountain near the holy 
  city of Qom that would be far harder to hit from the air. 
According to Ronen Bergman, senior military analyst for Israel's Yediot 
  Ahronot newspaper and the author of a forthcoming book on Mossad, that makes 
  a strike necessary well before Iran actually perfects its program. 
"Today Israeli intelligence talks of what is known as the 'framework of 
  immunity'," he said. "In other words, it is not the point at which 
  Iran acquires a nuclear device, but the point at which the project has 
  reached such an advanced stage that a strike any time after would be 
  ineffective." 
An Israeli attack could probably manage at most a dozen targets, using more 
  than 100 F-15 and F-16 aircraft. 
Three German-designed Dolphin submarines equipped with conventional cruise 
  missiles could also be ordered into the Persian Gulf to take part, although 
  it is thought that Israel's Jericho-3 ballistic missiles are to inaccurate 
  to play a role. 
But how effective the mission would be is another matter. At best, Israel can 
  hope to delay Iran from building a bomb by two to four years, experts 
  assess. Optimists hope that within such a period, Iran's Islamist regime 
  could collapse and give may to a more moderate government. But it could 
  equally redouble its nuclear efforts, this time arguing that it now had 
  every right to produce a weapon. 
As Mr Panetta warned during a Pentagon briefing last Thursday, such a strike 
  would also have a "serious impact" on the region. Iran could 
  blockade the Straits of Hormuz, through which 25 per cent of the world's oil 
  exports are shipped, sending energy prices soaring. US military assets in 
  the Gulf could come also come under attack from Iranian Scud missiles. 
Iran would almost certainly fire its Shahab ballistic missiles at Israeli 
  cities and press Hizbollah and Hamas, the militant Islamist groups it funds 
  and equips, to unleash their huge rocket arsenals from their bases in 
  Lebanon and Gaza. 
Despite this, last week Mr Barak - making a rare venture in such sensitive 
  territory - predicted 
  that fewer than 500 fatalities would arise "if people stayed at home". 
Such are both the political and military risks involved that many Israelis say 
  it is inconceivable that Mr Netanyahu would go to war without the United 
  States alongside him. 
"I think personally that if such action is taken, there will be come kind 
  of consultation with the United States," said Ilan Mizrahi, Mossad's 
  former deputy director and Israel's national security adviser until 2007. 
"If Iran breaks all the rules, then military action will be needed, but 
  definitely not alone by a tiny country like Israel," added Uzi Eilam, a 
  retired general who held senior positions at the Israeli defence ministry. 
But not everyone is so sure. Mr Obama's willingness to take on Iran militarily 
  is openly questioned in Israel. And while many Israelis do not believe Iran 
  has any intention of actually firing a nuclear missile at them, the the key 
  question is whether their prime minister is one of them. 
In Mr Netanyahu's eyes, Iran's president, Mahmoud Ahmadinejad, is another "Hitler" 
  whose aim is to complete what the Holocaust failed to do by wiping out the 
  Jewish race. 
"People outside Israel don't understand how profound memories of the 
  Holocaust are, and how they affect future policy making," said Mr 
  Bergman, the military analyst. "At the end of the day, this policy of 
  'never again' would dictate Israel's behaviour when intelligence comes 
  through that Iran has come close to a bomb."