For months, Israeli Prime Minister Benjamin Netanyahu and Defence Minister Ehud Barak have been touting the idea of a pre-emptive military strike against Iran to stop it from developing a nuclear bomb.

But now they find themselves increasingly under fire here at home for their tough talk about Iran and military options.

Just in the past week, the government has had to face down a growing barrage of criticism from former top security and military officials, as well as from former prime minister Ehud Olmert.

They all took issue with the Netanyahu assessment of just how far along Tehran is with its nuclear program and, more importantly, what can be done to stop it.

There are some here who suggest these attacks are part of some pre-election power struggle, as Netanyahu is said to be contemplating an early election call this year. Others see them as a larger piece of Israel's ongoing existential debate.

Whatever the case, by being played out day after day in Israeli media the criticism is adding to what appears to be a widening gulf between the country's political leadership and its security establishment.

"I have no faith in the current leadership, which must lead us in an event on the scale of war with Iran or a regional war," said Yuval Diskin, the former chief of Israel's domestic security service, Shin Bet, until his retirement a year ago.

Former Israeli security chief Yuval Diskin warns against 'messianic' leaders. (Oded Balilty/Associated Press)

"I don't believe in a leadership that makes decisions based on messianic feelings," Diskin told a public meeting in central Israel last week.

"They are misleading the public on the Iran issue. They tell the public that if Israel acts, Iran won't have a nuclear bomb. This is misleading. Actually, many experts say that an Israeli attack would accelerate the Iranian nuclear race."

Olmert weighs in

Diskin's assessment followed similar criticism from another ex-top security official, Meir Dagan, the former head of Israel's foreign intelligence agency Mossad, who has been critical of talk of an attack on Iran for almost a year now.

It also came just two days after the current chief of staff of the Israeli Defence Force, Lt.-Gen. Benny Gantz, publicly contradicted the prime minister, in interviews with Israeli newspaper by saying he didn't believe Iran had decided yet to obtain nuclear weapons and that its leadership is "very rational."

Dagan's view is that an Israeli attack on Iran would lead to a regional war that would have a "devastating impact" on the Jewish state and that a pre-emptive strike by Israel, presumably with U.S. help, would not stop Iran's nuclear weapons program.

It was a theme he reiterated on the weekend at a New York conference sponsored by the Jerusalem Post and attended by many U.S. supporters of Netanyahu, where he also praised Diskin.

But his remarks then were largely overshadowed by former Israeli prime minister Ehud Olmert, at the same conference, who jumped head first into the growing debate about Iran.

"A nation has the right to determine what it should do to defend itself," Olmert said. "But when at the same time we ask the United States and other countries to provide us with the means to do it, no one is entirely independent to act, irrespective of the positions and attitudes and policies of other countries."

A centre-right opponent of Netanyahu's Likud party in his day, Olmert was booed at times for his remarks, the New York Times reported. But he wouldn't back down.

"As a concerned Israeli citizen who lives in the state of Israel with his family and all of his children and grandchildren," he said, "I love very much the courage of those who live 10,000 miles away from the state of Israel and are ready that we will make every possible mistake that will cost lives of Israelis."

'Cannot be duped'

Plenty of military experts have weighed in to say that it would be difficult for Israel alone to cause substantial damage to Iran's nuclear operations because of a lack of specialized "bunker bombs" needed to penetrate the layers of rock shielding these facilities.

Israeli Prime Minister Benjamin Netanyahu (second from right) attends Memorial Day ceremony in Jerusalem on April 24, 2012. (Reuters)

The U.S., Israel's long-time supporter, has those munitions. But Barack Obama and his administration have worked to cool the rhetoric flowing from the Israeli government.

One leading Iran expert in Israel told me recently the White House worries about being dragged into a potential conflict, and having to finish what Israel started. He also says Washington is wary of a spike in oil prices during the presidential election campaign this year.

Still, U.S. diplomatic pressure hasn't succeeded in getting Netanyahu or Barak to tone things down.

In early April, Netanyahu went so far as to criticize Obama and UN Security Council members for giving Iran what he called "a freebie" on its nuclear program.

Later, speaking at a Holocaust Memorial Day, the prime minister warned that Iran was "feverishly working to develop atomic weapons" to achieve the goal of destroying Israel.

For his part, the defence minister told foreign journalists this week that Israel "cannot afford to be duped" by Iran.

"I have enough experience to know by now that a military option is not a simple one," Barak said. "It would be complicated with certain associated risks.

"But a radical Islamic Republic of Iran with nuclear weapons would be far more dangerous — both to the region and to the whole world."

With Israeli election talk now in the air, how much of this tough rhetoric is for domestic political consumption is difficult to gauge.

A poll conducted for the Jerusalem Post last week found that fewer than half of Israelis would support an independent attack on Iran. Other surveys, however, have found that about three-quarters of Israelis view Iran as an "existential threat" to the Israeli state.

At the same time, as their leaders have ratcheted up their words, Israeli peace groups are also making their presence felt. A few hundred people gathered in Tel Aviv last month to call on their government to stick to sanctions, not bombs, when dealing with Iran.

And the organizers of the "Israel Loves Iran" movement, a Facebook campaign that has drawn attention around the world, have been hanging posters of ordinary Israelis reaching out to Iranians.

The group's Facebook page has received more than 63,000 likes.