Less than a month before Hamas fighters blew through Israel's high-tech "Iron Wall" and launched an attack that would leave more than 1,200 Israelis dead, they practised the move in a very public dress rehearsal.

A slickly produced two-minute propaganda video posted to social media by Hamas on Sept. 12 shows fighters using explosives to blast through a replica of the border gate, sweep in on pickup trucks and then move building by building through a full-scale reconstruction of an Israeli town, firing automatic weapons at human-silhouetted paper targets.

The Islamic militant group's live-fire exercise dubbed operation "Strong Pillar" also had militants in body armour and combat fatigues carrying out operations that included the destruction of mock-ups of the wall's concrete towers and a communications antenna, just as they would do for real in the deadly attack last Saturday (Oct. 7).

While Israel's highly regarded security and intelligence services were clearly caught flatfooted by Hamas' ability to breach its Gaza defences, the group appears to have hidden its extensive preparations for the deadly assault in plain sight.

In a separate video posted to Telegram from last year's Strong Pillar exercise on Dec. 28, Hamas fighters are shown storming what appears to be a mockup Israeli military base, complete with a full-size model of a tank with an Israeli flag flying from its turret. The gunmen move through the cinderblock buildings, seizing other men playing the roles of Israeli soldiers as hostages.

Michael Milshtein, a retired Israeli colonel who previously led the military intelligence department overseeing the Palestinian territories, said he was aware of the Hamas videos, but he was still caught off guard by the ambition and scale of Saturday's attack.

"We knew about the drones, we knew about booby traps, we knew about cyberattacks and the marine forces ... The surprise was the coordination between all those systems," Milshtein said.

The seeds of Israel's failure to anticipate and stop Saturday's attack go back at least a decade. Faced with recurring attacks from Hamas militants tunnelling under Israel's border fence, Prime Minister Benjamin Netanyahu proposed a very concrete solution - build a bigger wall.

With financial help from US taxpayers, Israel completed construction of a $1.1 billion project to fortify its existing defences along its 40-mile land border with Gaza in 2021. The new, upgraded barrier includes a "smart fence" up to 6-metres (19.7 feet) high, festooned with cameras that can see in the dark, razor wire and seismic sensors capable of detecting the digging of tunnels more than 200 feet below. Manned guard posts were replaced with concrete towers topped with remote-controlled machine guns.

Hamas forces also struck a nearby army base near Zikim, engaging in an intense firefight with Israeli troops before overrunning the post. Videos posted by Hamas show graphic scenes with dozens of dead Israeli soldiers.

They then fanned out across the countryside of Southern Israel, attacking kibbutzim and a music festival. On the bodies of some of the Hamas militants killed during the invasion were detailed maps showing planned zones and routes of attack, according to images posted by Israeli first responders who recovered some of the corpses. Israeli authorities announced Wednesday they had recovered the bodies of about 1,500 Islamic fighters, though no details were provided about where they were found or how they died.

Military experts told the AP the attack showed a level of sophistication not previously exhibited by Hamas, likely suggesting they had external help.

"I just was impressed with Hamas's ability to use basics and fundamentals to be able to penetrate the wall," said retired U.S. Army Lt. Col. Stephen Danner, a combat engineer trained to build and breach defences. "They seemed to be able to find those weak spots and penetrate quickly and then exploit that breach."

Ali Barakeh, a Beirut-based senior Hamas official, acknowledged that over the years the group had received supplies, financial support, military expertise and training from its allies abroad, including Iran and Hezbollah in Lebanon. But he insisted the recent operation to breach Israel's border defences was homegrown, with the exact date and time for the attack known only to a handful of commanders within Hamas.

Details of the operation were kept so tight that some Hamas fighters who took part in the assault Saturday believed they were heading to just another drill, showing up in street clothes rather than their uniforms, Barakeh said.

Last weekend's devastating surprise attack has shaken political support for Netanyahu within Israel, who pushed ahead with spending big to build walls despite some within his own cabinet and military warning that it probably wouldn't work.

In the days since Hamas struck, senior Israeli officials have largely deflected questions about the wall and the apparent intelligence failure. Rear Adm. Daniel Hagari, the chief spokesman for the Israel Defense Forces, acknowledged the military owes the public an explanation, but said now is not the time.

"First, we fight, then we investigate," he said.

In his push to build border walls, Netanyahu found an enthusiastic partner in then-President Donald Trump, who praised Netanyahu's Iron Wall as a potential model for the expanded barrier he planned for the U.S. Southern border with Mexico.

Under Trump, the U.S. expanded a joint initiative with Israel started under the Obama Administration to develop technologies for detecting underground tunnels along the Gaza border defences. Since 2016, Congress has appropriated $320 million toward the project.

But even with all its high-tech gadgets, the Iron Wall was still largely just a physical barrier that could be breached, said Victor Tricaud, a senior analyst with the London-based consulting firm Control Risks.

"The fence, no matter how many sensors ... no matter how deep the underground obstacles go, at the end of the day, it's effectively a metal fence," he said. "Explosives, bulldozers can eventually get through it. What was remarkable was Hamas's capability to keep all the preparations under wraps."

Allies who share intelligence with Israel said security agencies were misreading reality.

The BBC and other outlets reported Egyptian intelligence official said Egypt, which often serves as a mediator between Israel and Hamas, had spoken repeatedly with the Israelis about "something big," without elaborating. He said Israeli officials were focused on the West Bank and played down the threat from Gaza. Netanyahu's government is made up of supporters of Jewish West Bank settlers who have demanded a security crackdown in the face of a rising tide of violence there over the last 18 months.

"We have warned them an explosion of the situation is coming, and very soon, and it would be big. But they underestimated such warnings," said the official, who spoke to the Associated Press on condition of anonymity because he wasn't authorised to discuss the content of sensitive intelligence discussions with the media.

Israel has also been preoccupied and torn apart by Netanyahu's judicial overhaul plan. Netanyahu had received repeated warnings by his defence chiefs, as well as several former leaders of the country's intelligence agencies, that the divisive plan was chipping away at the cohesion of the country's security services.

In the immediate aftermath of the attacks, we saw it proclaimed as 'Israel's 9/11', referring to the September 11, 2001 attacks that brought down the Twin Towers of the World Trade Centre in New York.

In fact, it is true that Israel has been dealt the biggest blow in its history at a time when the Palestinian national movement is arguably at its lowest ebb, having practically fallen off the world's conscience. This should give any government in Israel pause for thought, especially over the wisdom of its continued occupation of Palestinian lands, one of the many policies that contribute to the apartheid conditions under which Palestinian lives wither away even today. The peace process has been killed off by a succession of rightwing governments in Israel, most of them led by Netanyahu, and it is increasingly fashionable these days, to say "The two-state solution is dead."

These, along with the Israeli military or IDF's frequent violations of the sanctity of Al Aqsa Mosque, the increased settler activity including violence and illegal expansions, and their increasing propensity to treat Palestinians with callous disregard, would surely come back to bite them. No one could have imagined just how.

Israel's right to defend itself

President Joe Biden on Wednesday condemned the weekend attack by Hamas militants on Israel as the deadliest day for Jews since the Holocaust as the number of U.S. citizens killed in the fighting ticked up to at least 22.

"This attack was a campaign of pure cruelty - not just hate, but pure cruelty - against the Jewish people," Biden told Jewish leaders gathered at the White House.

Beyond the 22 known to have been killed, the State Department said at least 17 more Americans remain unaccounted for in a war that has already claimed more than 2,200 lives on both sides. A "handful" of U.S. citizens are among the estimated 150 hostages captured by Hamas militants during their shocking weekend assault on Israel, White House national security spokesman John Kirby said Wednesday.

Kirby said the USS Dwight D. Eisenhower and its ships would be an "available asset" if necessary. The USS Gerald R. Ford, the Navy's most advanced aircraft carrier, and its strike group have already arrived in the Eastern Mediterranean.

The attack has raised questions about the role of Iran, the main sponsor of Hamas, and whether it was directly involved in the operation. But the US has collected information that suggests senior Iranian government officials were caught off guard by the multi pronged assault, according to a U.S. official who wasn't authorised to discuss the matter publicly and spoke on condition of anonymity. That piece of intelligence has informed White House officials publicly asserting that it has not yet seen evidence of direct involvement by Iranians in the planning or execution of the Hamas attack.

"We haven't seen anything that tells us they have specifically cut checks to support this set of attacks, or that they were involved in the training. And obviously, this required quite a bit of training by these terrorists," Kirby said, though he added that the U.S. will continue to look at the intelligence "and see if that leads us to a different conclusion."

Biden at the roundtable with Jewish leaders suggested the deployment of US military ships was a not-so-subtle message to Iran and other actors in the region. "We made it clear to the Iranians: Be careful."

Israel's military meanwhile, directed the evacuation of northern Gaza, a region that is home to 1.1 million people, within 24 hours Friday, as Israel pressed ahead with its objective to eradicate Hamas. But is that really possible?

The militant group is seen as the Palestinians' fulfilment of their own right to resist occupation through any means possible, including armed struggle. It has ruled Gaza since 2007 with an fist, throwing out Fatah. Thus they enjoy a fair bit of support among the civilian population as well.

Occupation is provocation

Most importantly, as long as the status quo persists, killing off Hamas activists would only perpetuate the conditions to give birth to more among the civilian population. And so it has been disquieting to see one Western leader after another line up to give Israel and its army carte blanche, in effect, to extract whatever price they wish from the Palestinians, for the attack carried out by Hamas, that is frequently being described as 'unprovoked'.

Almost completely absent from the discussions has been any sort of acknowledgement of the role played by Israel's 56-year occupation of Palestinian territory. Occupation is a state of constant, permanent provocation. Gaza, on which Israel has maintained a blockade from air, land and sea for 16 years, is described as 'the world's largest open-air prison'. Imagine the life of the Rohingya refugees, only on your own land following illegal eviction. To try and pass off anything the Palestinians do as 'unprovoked' is either wilfully blind, or drowning in hubris.

The order to evacuate could signal an impending ground offensive, though the Israeli military has not yet confirmed such an appeal. On Thursday it said that while it was preparing, no decision had been made yet to commence the ground offensive in Gaza

The order, delivered to the UN, comes as Israel presses an offensive against Hamas militants. U.N. spokesman Stéphane Dujarric called the order "impossible" without "devastating humanitarian consequences."

Panicked rumours of an evacuation had begun to spread in north Gaza, home to almost half the population of the territory, in the early morning Friday.

A ground offensive in Gaza, which is ruled by Hamas and where the population is densely packed into a sliver of land only 40 kilometres (25 miles) long, would likely bring even higher casualties on both sides in brutal house-to-house fighting.

Hamas' assault last Saturday (Oct. 7) and smaller attacks since have killed more than 1,300 people in Israel, including 247 soldiers - a toll unseen in Israel for decades - and the ensuing Israeli bombardment has killed more than 1,530 people in Gaza, according to authorities on both sides. Israel says roughly 1,500 Hamas militants were killed inside Israel, and that hundreds of the dead in Gaza are Hamas members. Thousands have been wounded on both sides.

Biden warned other countries not to get involved in the conflict in hopes of exploiting the chaos. "For anyone thinking (of taking) advantage of the situation," he said in a speech Tuesday, "I have one word: Don't."

However, given the grief and outrage in Israel over Saturday's attack, anything linking Iran to the assault would drastically increase pressure on long-embattled Prime Minister Benjamin Netanyahu to retaliate against Tehran. Netanyahu, who has campaigned as being Israel's self-described protector, has pointed at Iran as his nation's No. 1 regional enemy. He has repeatedly warned he wouldn't allow Iran to obtain a nuclear weapon - something his nation possesses.

And while Iran maintains its program is peaceful, it enriches uranium closer than ever to weapons-grade levels. That makes those facilities, as well as military bases in Iran and abroad, possible targets for Netanyahu.

"Citizens of Israel, we are at war, not in an operation or in rounds, but at war," Netanyahu told the nation after Saturday's attack. How long, or wide-ranging that war will become remains to be seen.

Additional reporting from AP, Middle East Eye