Israeli forces prepare for grinding urban war in Gaza

On Friday, Israel called for civilians to evacuate from Gaza City, including United Nations personnel, to the south within 24 hours.

The impact of last weekend's attack by Hamas -- the worst in Israel's history -- has left little doubt about the scale of the upcoming operation, with the intense aerial bombardment serving as preparation for a major ground assault, say analysts.

The strikes are designed "to eliminate Hamas command and control, key leaders, tunnels, weapons caches and rocket launchers to reduce the risk of rocket strikes against Israeli civilians and the risks to (Israeli army) members during a ground operation," said defence expert Alex Plitsas of the Atlantic Council.

The prospect is now of Gaza -- one of the most densely populated places on the planet -- joining a list of urban areas reduced to rubble by military operations that includes Fallujah in 2004, Mosul in 2017 and Mariupol in 2022.

Gaza already saw devastating clashes in 2014, when Israel mobilised 75,000 reservists for an invasion that lasted 50 days, according to John Spencer of the Modern War Institute at the US military academy West Point.

This time, it has called up 300,000.

"The Israelis will send all their elite units, armoured vehicles, mechanised infantry, sappers, commandos and special forces," said Pierre Razoux of the Mediterranean Foundation of Strategic Studies.

They will have support from artillery, drones, fighter jets and combat helicopters.

The initial objective could be to slice the Gaza Strip in two, separating Rafah in the south from Gaza City in the north, said Razoux.

He expects "mechanised and armoured operations to seize the main roads, as in Beirut in 1982, before a coordinated assault in all directions" by land, sea and air.

The invasion will likely be launched at night, Razoux added, since Hamas is deprived of electricity while Israeli fighters are equipped with the latest night-vision devices that allow them to see even through walls.

- 'House-to-house' -

Technological superiority offers no easy solutions, however.

Urban warfare always constitutes "one of the most complex tactical and logistic environments" for any army, said Andrew Galer, of British intelligence firm Janes.

Hamas fighters operate in a maze of narrow alleys and a network of tunnels that Israeli intelligence services can only partially know.

"In urban warfare history, a single building as a strongpoint can take days, weeks, or months to clear," said Spencer.

Hamas is also heavily armed.

In 2014, it deployed 2,500-3,500 fighters equipped with rockets, mortars, anti-tank guided missiles, grenade launchers, automatic rifles and small weapons, he said.

Its armoury has only expanded since, Spencer added, particularly with the addition of the "full spectrum of drones -- from military-grade suicide drones to commercial, off-the-shelf quadcopters modified to drop munitions."

Civilians in Gaza face a terrifying ordeal.

More than 423,000 have already fled their homes, but they face few options for escape with Gazas borders sealed shut on all sides.

Israeli Prime Minister Benjamin Netanyahu, knowing his entire political legacy is on the line, has set a maximalist goal.

"Just as ISIS was crushed, Hamas will be crushed," Netanyahu said, referring to the Islamic State group.

That sets the Israeli military up for a long fight.

"The only way for Israel to achieve its goal of eliminating Hamas's military capabilities is house-to-house, block-to-block urban warfare," said Plitsas, the Atlantic Council defence expert.

"This could take several months given the size of Gaza, the number of terrorists willing to fight, the extent of terrorist weapons caches, and the size of the civilian populace."