JERUSALEM (Reuters) - Menachem Begin did not pull his punches. In 1981, as work neared completion on an Iraqi nuclear reactor that Israel believed would produce plutonium for warheads, the Israeli prime minister dispatched eight F-16 bombers to destroy the plant. Begin later said that the raid was proof his country would "under no circumstances allow the enemy to develop weapons of mass-destruction against our people".
The event defined a strategy that became known as the "Begin Doctrine" and is best summed up by the phrase "the best defense is forceful preemption."
Israel's message is now more guarded. In a civil defense drill of unprecedented scale last June, sirens summoned schoolchildren to shelters, radars searched the skies for computer-simulated missile salvoes, and Prime Minister Benjamin Netanyahu's cabinet descended into the Jerusalem foothills to inaugurate a nuclear bunker with a mock war-session.
Why would a country that has long vowed to stop its foes attaining nuclear weapons need a nuclear bunker? The question highlights a new, reluctant restraint that has quietly infused Israeli decision-making in recent years as regional threats have grown more complex and sapped the applicability of classic force of arms. Nowhere is this felt more than in the Netanyahu government's posture toward Iran.
The spin of the Islamic republic's uranium centrifuges stirs mortal fear in the Jewish state. In defiance of western pressure to curb the project's bomb-making potential, Iran has pushed on with its nuclear program, saying it has no hostile designs. The International Atomic Energy Agency will say this week that Iran now has the ability to build a nuclear weapon, the Washington Post has reported. Israeli officials have long hinted they may launch a preemptive strike.
That threat has taken on fresh intensity in the two years since Netanyahu -- a right-wing ideologue like Begin -- assumed office. Media speculation that Israel might launch a unilateral strike has surged again in the past two weeks.
In October, the dean of Israeli pundits, Nahum Barnea, suggested on the front page of the best-selling Yedioth Ahronoth newspaper that the government was hatching an imminent attack. Days later Netanyahu warned of the "direct and heavy threat" posed by Iran's nuclear program and then, on November 2, Israel test-fired a missile. The same day the military said it had completed air exercises in Sardinia, "practicing operations in (a) vast, foreign land".
Such talk robs Israel of some of the element of surprise if it really is planning an assault on Iran. Could it instead be a loud reminder to the rest of the world of its problem with Iran in the hope that Washington or another power might intercede?
Interviews in recent months with government and military officials -- most speaking on condition of anonymity -- and independent experts suggest that Israel prefers caution over a unilateral strike against the Iranians.
The country has been digging in under sophisticated strategic defenses with at least as much energy as it has been preparing offensive options. Netanyahu's own circumspection is instructive.
As opposition leader in 2005, he told Israel Radio that in dealing with Iran he would "pursue the legacy" of Begin's "bold and courageous move" against Iraq. But as prime minister he has been less explicit -- both in public and, to judge by leaked U.S. diplomatic cables dated as recently as 2010, in closed-door meetings he and aides held with visiting American delegates. Instead, Israel has pushed its demand that world powers stiffen sanctions on Tehran and that the United States provide the vanguard of any last-ditch military move.
"The military option is not an empty threat, but Israel should not leap to lead it. The whole thing should be led by the United States, and as a last resort," Deputy Prime Minister and Strategic Affairs Minister Moshe Yaalon told Israel's Army Radio.
The Prime Minister's Office declined to comment directly on whether Netanyahu felt bound by the Begin Doctrine regarding Iran.
Israelis have known for years that an attack on Iran would be much more difficult than their Iraq strike. Iran is larger, more distant and, perhaps because it learned the lessons of Iraq, has built numerous and well-fortified facilities. Taking these out would require a sustained campaign by the Israeli air force, which is more geared for precision strikes through the use of advanced technology.
"With Iran it's a different project. There is no one silver bullet (with which) you can hit," a senior Israeli defense official told Reuters, in a rare admission of his country's tactical and strategic limitations.
Iran has guerrilla allies across its borders in Lebanon and Gaza, against whom Israel fought costly wars in 2006 and 2009. With the Netanyahu government facing growing isolation -- its impasse with the Palestinians is deepening; its alliances with Turkey and Egypt fraying -- Israel acknowledges that it is reluctant to go it alone against the Iranians.
"We have to learn that the situation is changing, the region is changing. Not everything that was possible before is possible now and new possibilities open up," said Dan Meridor, deputy prime minister in charge of Israel's nuclear and intelligence affairs.
It was Meridor who recommended "defense" as a fourth pillar of Israeli national security in a secret memorandum he authored on behalf of the government in 2006. That report added to the three doctrinal "D's" set out by Israel's first prime minister, David Ben-Gurion, soon after the country's founding in a 1948 war with neighboring Arabs: detect enemies' threats, deter them with the promise of painful retribution and, if hostilities nonetheless ensue, defeat them quickly on their own turf.
"This was something counter-intuitive for Israel, especially for the military. Israelis like to be on the attack, not on the defensive," Meridor said.
While he declined to discuss the prospect of military action against Iran, Meridor distanced himself from the idea that the Begin Doctrine commits Israel to such a course.
"I am not sure what people mean when they use this term. In any event, there is no contradiction between any attack doctrine and a defense doctrine. They are complementary. If the attack doesn't does not solve the problem, then you need to be able to defend yourself."
The most obvious example of Israel's shifting stance is its pioneering missile shield, which incorporates a network of radar-guided interceptors designed to shoot down everything from the ballistic Shehab and Scud missiles of Iran and Syria to the lower-flying, Katyusha-style rockets of Hezbollah and Palestinian guerrillas.
In artist renditions at Israeli defense conferences, the shield covers Israel in overlapping bubbles, like some huge plexiglass Babushka doll. That sits in contrast to the publicity images of warplanes or tank columns taking the offensive, which used to define Israel's military self-image.
The shield is a work in progress. Its lowest tier, the short-range Iron Dome interceptor, was deployed this year. The top tier, Arrow, is designed to blow up threats above the atmosphere, high enough to safely vaporize a nuclear warhead. The Arrow III upgrade, due for live trials by early 2012, features a detachable satellite that will collide, kamikaze-like, with incoming missiles in space.
Many Israelis rankle at the idea that the shield, which was conceived following Iraq's use of conventional Scud missiles during the 1991 Gulf war, should be relied on to stave off nuclear catastrophe.
"Hermetic protection will be impossible," Colonel Zvika Haimovitch of the air defense corps told Tel Aviv University's Institute for National Security Studies (INSS) in a September 5 speech. "I assess that, in any conflict, rockets and missiles will fall here."
But others, including INSS scholar and retired Israeli general Shlomo Brom, argue for Israel's defensive posture to be expanded, and perhaps even for the secrecy to be eased around the country's own, reputed atomic arsenal. Aiming to avoid a regional arms race and skirt international anti-proliferation scrutiny, Israel currently neither confirms nor denies having the bomb.
"The answer is mutual deterrence, with the other side knowing the price it would pay for launching a nuclear strike -- mutual destruction," said Brom.
Like Meridor, Brom dismissed the suggestion that the Iraqi reactor strike set a precedent for a potential Israeli strike on Iran. He notes Israel's decision not to take military action against suspected chemical weapons programs of Syria and Iraq has already undermined the Begin Doctrine.
Israel did loose its jets on Syria in 2007, to destroy a desert installation that Washington later described as a nascent, North Korean-supplied atomic reactor. Damascus denied having such a facility and Israel has never formally taken responsibility for the raid. In his memoir, former U.S. President George W. Bush said Israel's prime minister at the time, Ehud Olmert, preferred the reticence "because he wanted to avoid anything that might back Syria into a corner and force (President Bashar) Assad to retaliate".
Former U.S. Vice President Dick Cheney was not surprised that Israel went it alone. "I ... remembered 1981, when the Israelis had ignored world opinion and launched an air strike to destroy a nuclear reactor Saddam Hussein was building at Osirak in Iraq," Cheney wrote in his autobiography. "For the Syrians and the North Koreans ... the private message was clear -- Israel would not tolerate this threat."
But some argue the attack on Syria was designed to send a message to Iran.
"We noted a whole lot of Iranian interest in what happened in Syria -- trips by consultants, intense communication," said a one-time adviser to Olmert, breaking Israel's official silence around the episode.
By tackling Syria, Israel hoped to make the Iranians think twice about pursuing their nuclear program. To illustrate, the ex-adviser cited "Family Business", a 1989 crime drama in which a veteran jailbird, played by Sean Connery, counsels his grandson on how to survive prison: "You pick out a tough guy, kick his ass right away ... Word gets around, and it makes your time easier."
Of course, the Americans also took note. Visiting Israel last month, U.S. Defense Secretary Leon Panetta was asked by a reporter about the possibility that the 2007 sortie augured an Israeli attack on Iran. Panetta did not answer directly. He made clear that Washington disapproved of the idea of unilateral action, but said "a number of countries in this region recognize the threat from Iran," and that concerned countries would "work together to do whatever is necessary to make sure that they do not represent a threat to this region."
Israelis often question U.S. President Barack Obama's resolve in the Middle East. But even if he loses power in next year's presidential election to a more hawkish Republican, it may be too late for Israel, which predicted last January that Iran could have its first nuclear device in two years. That forecast was echoed by Britain.
"If they (Israel) feel they could achieve their objective, or at least initiate the kind of conflict that would meet their objective, through a one-off strike, that would be feasible," said Richard Kemp, a retired British army colonel who has studied Israeli strategy.
Israel's military does not comment on prospective operations. But many in Israel's defense establishment have gone out of their way to downplay the feasibility of a unilateral attack. Former Mossad spymaster Meir Dagan has repeatedly ridiculed the idea in briefings to Israeli reporters.
"Attacking the reactors from the air is a stupid idea that would have no advantage," he said in May. "A regional war would be liable to unfold, during which missiles would come in from Iran and from Hezbollah in Lebanon."
The Mossad under Dagan, who retired in January, is widely believed to have been behind the Stuxnet software attack on Iran's nuclear computer systems as well as the assassination of several Iranian scientists. Israel has neither confirmed nor denied those allegations.
And even Netanyahu has shown signs of being gun shy -- certainly when compared to his predecessor, the centrist Olmert, who ordered the Israeli wars in Lebanon and Gaza.
The prime minister's swift deployment of short-range Iron Dome interceptors outside the Hamas-ruled territory of Gaza in April helped scotch Palestinian rocket attacks that might have otherwise drawn an Israeli invasion.
In January 2010, after the United Arab Emirates accused the Mossad of murdering a senior Hamas arms procurer in his Dubai hotel room, Israeli officials whispered that such skullduggery was preferable to the civilian toll of another Gaza war.
Keeping the world guessing as to how -- and if -- a confrontation might happen is in itself part of Israel's strategy.
"I hope that the Iranians see an Israeli conspiracy in this," said Yaalon of the mixed messages emanating from the Netanyahu government and its detractors, like Dagan. "That could help."
Edited by Simon Robinson, Crispian Balmer, Chris Kaufman and Sara Ledwith