The devastating failure of the Israeli intelligence services to predict the deadly Hamas incursion stemmed from a total misunderstanding of the militant group, experts have said.

Israel was taken by complete surprise early on Saturday morning as Hamas fired thousands of rockets from the Gaza Strip at the country, while more than a thousand fighters gunned down hundreds of people and took at least 100 hostages.

Israeli soldiers embarked on fierce battles with the militants holed up in southern communities, as the air force began striking strategic targets in Gaza.

By Monday morning, official estimates put the number of Israeli civilians and soldiers killed at over 700, a huge toll for a country of less than 10 million people.

"It's a huge failure of the intelligence system and the military apparatus in the south," said retired military general Yaakov Amidror, who served as Israel's national security advisor in 2011-2013.

But beyond the operational failure of Israel's vaunted intelligence services to detect the well-organized attack and the army's inability to block it, Israel's broader take on Hamas was entirely flawed, Amidror said.

"We made a huge mistake, including me, in believing a terror organization can change its DNA," he told journalists.

"We heard from our friends around the world that they're behaving more responsibly, and we believed it in our stupidity," said Amidror, currently a senior fellow at the Jerusalem Institute for Strategy and Security.

'Unprecedented' restraint

Hamas is considered a terrorist group by Israel, the United States and the European Union.

The group has controlled the impoverished Gaza Strip since it ousted loyalists of Palestinian president Mahmud Abbas in 2007, two years after Israel withdrew from there.

Created in 1987 by a group of militants close to the Muslim Brotherhood organization, its charter calls for an Islamic state throughout Palestinian territories and the group set up aid programs focused on social welfare schools.

Before Saturday's assault, Israel had fought four wars with Gaza militants, the last one in 2021.

These wars were marked by devastating air strikes as Israel sought to destroy Hamas' military capabilities, while the militants rained down rockets across the border.

In an attempt to win some peace, Israel had recently increased work and trade permits for Gazans, with about 18,500 laborers providing significant income to the densely-populated coastal enclave where around half of the population is unemployed.

Israel believed that economic incentives, wedded with the implicit threat of military force, had made Hamas lose its appetite for violence.

Earlier this month, Israel's national security advisor Tzachi Hanegbi said that for the past two years Hamas has not initiated any rocket launches, as part of its decision to curb its violence in an "unprecedented" manner.

"Hamas is very restrained, and understands the meaning of further defiance," he said in an interview with army radio on 1 October.

'Writing on the wall'

To Michael Milshtein, head of the Palestinian Studies Forum at the Tel Aviv university's Dayan Center, such remarks show "we totally misunderstood Hamas".

"The notion of economic incentives that would diminish Hamas' motivation for terror and even cause the public to go against it totally collapsed," he told AFP.

"You're dealing with a radical, ideological organization. Do you really think you can buy their ideology out? Bend it? This is a total misunderstanding, and probably included wishful thinking.

"While we believed that a radical body that takes power gradually becomes moderate, they were gaining strength and preparing the next stage of their war."

Milshtein, a retired intelligence officer who was an advisor to COGAT, the Israeli defense body responsible for Palestinian civilian affairs, said the Hamas leadership had been publicly professing its intention to carry out an attack just like Saturday's.

"The operation was planned for nearly a year, which is amazing because this is a year in which Israel kept on increasing the amount of labor permits and concessions," he said.

"The Israeli conception was that Hamas doesn't want an escalation," Milshtein said.

"The writing was on the wall. They just didn't want to believe it was true."

Israel's leadership was swift to indicate that the penny has dropped.

On Saturday, Israel's Defence Minister Yoav Gallant said that when he was head of the military's southern command in 2009, he wanted to "break the neck" of Hamas but was stopped by the political echelon.

Now, as the man who along with Prime Minister Benjamin Netanyahu determines the course of the war, Gallant was no longer subject to restraints.

"We will change the reality on the ground in Gaza", he vowed.

"What was before, will be no more."