Gaza, a lethal labyrinth made by Hamas to thwart invading Israeli troops

The Israeli army's death toll in besieged Gaza is already almost twice as high as during a ground invasion in 2014, a reflection of how far it has pushed into the enclave and of Hamas' effective use of guerrilla tactics and an expanded arsenal.

Israeli military experts, an Israeli commander and a Hamas source, described how the Palestinian resistance group had used a big weapons stockpile, its knowledge of the terrain and a vast tunnel network to turn Gaza's streets into a deadly maze.

At their disposal, they have arms ranging from drones rigged with grenades to anti-tank weapons with powerful twin charges.

Since Israel's ground invasion began in late October, about 119 Israeli soldiers have been killed as tanks and infantry thrust into the cities and refugee camps, based on official Israeli figures. About a quarter were tank crew.

That compares with 66 in the 2014 war, when Israel launched a more limited three-week ground invasion, but the goal then was not to eliminate Hamas.

"There is no comparing the scope of this war to 2014, when our forces mostly operated no deeper than a kilometre inside Gaza," said Yaacov Amidror, a retired Israeli major-general and former national security adviser who is now at the Jewish Institute for National Security of America [JINSA].

He said the army "has yet to find a good solution for the tunnels," a network hugely expanded in the past decade.

Prime Minister Benjamin Netanyahu said on Thursday Israel would wage war "until absolute victory".

Israeli officials have said it could take months before being complete. "It has been a challenge from day one," Ophir Falk, foreign policy adviser to Netanyahu, told the Reuters news agency, saying the invasion had come with a "huge price" in Israeli soldiers.

"We know that we're going to probably have to pay an additional price to complete the mission."

Heavy fighting

Hamas has posted videos on its Telegram channel this month showing fighters with bodycams weaving through buildings to launch shoulder-held rockets at armoured vehicles.

Videos released by the Hamas Military Wing on December 13 showed intense fighting in Gaza and Khan Younis.

The heavily edited footage depicted various scenes of armed individuals targeting and firing upon Israeli military vehicles. In some instances, apparent explosive devices are shown being placed underground and detonated.

Another, posted on December 7, was from Shejaiya, east of Gaza City, an area where both sides reported heavy fighting.

In a post on December 5, a camera emerges from a tunnel, like a periscope, to scan an Israeli camp where soldiers rested. The post said it was later hit by an underground blast.

In a recorded message, the Al-Qassam Brigades spokesman Abu Obeida said on Friday the Al-Qassam fighters killed and wounded many Israeli troops in different ambushes in the past five days.

He added that the Hamas fighters used bunker-busting grenades, destroying houses where Israeli soldiers were taking positions.

A Hamas source, who spoke to Reuters from inside Gaza on condition of anonymity, said fighters moved as close as possible to launch ambushes, "taking advantage of the land we know like no others do", often moving around or emerging from tunnels.

"There is a huge discrepancy between our power and their power, we don't fool ourselves," he said.

Hamas has not said how many of its fighters have been killed. Israel's military has claimed it has killed at least 7,000 without providing any proof.

Gaza authorities dismiss the Israeli figure, saying Israel's indiscriminate bombardment has killed nearly 19,000 Palestinians, 8,000 of whom are children and 6,200 women.

An Israeli commander, who fought in 2014, said the expanded scope of this war meant more troops were on the ground, giving Hamas the "defender's advantages", so higher troop casualties were to be expected.

Israel's Channel 12 television showed one army reservist unit, wary of booby-trapped doors, smashing through the wall of a building to enter a room to discover a munitions cache.

Mirroring tactics used in 2014, Israel's military has posted images on social media showing routes smashed through built-up areas by bulldozers so troops can avoid existing roads that might have landmines.

Even in some districts in north Gaza, where many buildings have been pounded into rubble, bouts of fierce fighting have persisted.

Bigger arsenal

"Hamas made some huge steps to build up its force since 2014," said Eyal Pinko, a former senior official with Israel's intelligence services who is now at Bar Ilan University's Begin-Sadat Center for Strategic Studies.

He said Hamas has some advanced arms, such as Russian-designed Kornet anti-tank missiles, adding Hamas had mastered building other weapons in Gaza, such as RPG-7 rocket-propelled grenades, and the fighters now had a bigger munitions reserve.

Hamas posts have said the group's weaponry includes "tandem" anti-tank weapons with two charges to pierce armour, which Pinko also said was in the group's arsenal.

Hamas videos often show big blasts when vehicles are hit.

"Hamas may post their new weapons and tactics, [but] in principle, it remains a guerrilla resistance movement," said Alexander Grinberg, a former Israeli military intelligence officer with the Jerusalem Institute for Strategy and Security.