JERUSALEM/GAZA: Israel's military has rallied after an initial chaotic scramble to halt an assault by Palestinian Islamist group Hamas and is retaliating with airstrikes on roads, buildings and other sites in Gaza while sending huge reinforcements towards the enclave.

To many of the 2.3 million residents of the strip of land that Israeli forces quit in 2005, the mobilisation and intense bombardment look ominously familiar: the prelude to a ground invasion and one that may match, or even eclipse, Israel's incursions in 2008 and 2014.

One Israeli security source told Reuters a ground offensive now looked inevitable.

"People feared the bombardment of the border area was a tactic to create scorched earth before tanks advance," said Yamen Hamad, a father of four who fled with his family and others from Beit Hanoun near Gaza's north border, where blast craters have made roads impassable and buildings nearby have been turned into rubble.

Israeli security sources said it took more than 48 hours to restore military cohesion, halt infiltrations and clear Hamas fighters from towns they stormed on Saturday in an operation that caught the Middle East's most powerful army off guard.

Using a web of deception and relying on motorbikes, paragliders and other basic equipment, Hamas fighters killed more than 1,000 Israelis and took scores of hostages - a move that potentially complicates any Israeli response.

But Israel's retaliation has nonetheless been fierce. The death toll from airstrikes on Gaza was at least 830 people on Tuesday and, according to U.N. figures, more than 180,000 had been made homeless.

One Israeli security source, who like others declined to be named, said he believed an Israeli ground invasion was "not preventable because of the heavy price that we paid. This will be after airstrikes by the air force."

'YOU CANNOT JUST ENTER'

The source said the objective was "softening the other side and within this, causing people to flee (built up areas). It is also about building force strength, strategy and surprise. You cannot just enter."

Smashing up roads has been a typical tactic in the prelude to two previous Israeli ground assaults in Gaza, disrupting communications and the movement of Hamas and other groups. When Israel enters, residents say its forces often bulldoze new routes for their vehicles to avoid landmines in existing roads.

But sending troops into a densely packed, urban environment is not an easy choice, even as Prime Minister Benjamin Netanyahu vows "mighty revenge" in response to the huge death toll meted out by the Hamas fighters in the worst breach in Israel's formidable defences since Arab armies attacked in 1973.

Giora Eiland, a former head of Israel's National Security Council, said airstrikes in Gaza "seemed very similar to previous Israeli operations" but that these tactics had not neutralised Hamas in the past.

A ground offensive could more effectively kill Hamas fighters and destroy the chain of command, Eiland said, but added: "The government is still reluctant in taking such an initiative because it might involve many, many more Israeli casualties."

Urban warfare erodes Israel's overwhelming superiority in firepower, pitting it against a group which is more battle hardened from previous conflicts and increasingly well-equipped by Iran. The group, which took power in Gaza in 2007, has also had years to build a network of tunnels, which helps fighters melt away. Israeli troops sometimes call it the "Gaza Metro".

In 2008, Israel lost nine soldiers during its incursion. In 2014, the number killed soared to 66.

This time, Hamas also has dozens of hostages it seized in the Oct. 7 operation - some of them soldiers but many civilians. It presents a huge challenge for a nation whose principle is to leave no one behind. In 2011, it agreed to exchange hundreds of Palestinian prisoners for one Israeli soldier, Gilad Shalit, who had been held captive for five years.

'PAY A HEAVY PRICE'

"Israel knows the great preparedness of the resistance factions and their ability to handle ground incursions," said Talal Okal, an analyst in Gaza who writes for the daily Al-Ayyam newspaper, saying Israel may yet hesitate over a land assault.

"It wants to make Gaza pay a heavy price but I don't think it is prepared to pay the heavier prices should they enter Gaza," he added.

Even as Israel masses forces on Gaza's border and mobilises hundreds of thousands of reservists, the government has not said whether or not it will send in troops.

Gaza residents said on Wednesday more roads were among sites hit overnight, including a key coastal road. Israel's military said targets included what it said was a Hamas surveillance camera network, weapons storage and manufacturing facilities and tunnels used by operatives.

Asked about a possible land invasion, Israeli military spokesperson Major Amir Dinar said: "We are striking Hamas infrastructure and we are going to strike hard and keep striking." He did not elaborate.

The Israeli prime minister's office and Foreign Ministry declined to comment.

Two Hamas spokespeople were not available for comment for this article.

A Palestinian fighter official, who declined to identified, said: "There is a history between 2008, 2014 and 2023. The resistance is no longer the same or that under-equipped."

"We are always prepared. If Israel sends more soldiers in, they will either become bodies or hostages," the official added.

Hamas has already proved to be a tougher and more capable force than Israel had expected by launching its Oct. 7 attack.

The Palestinian operation marked a massive intelligence failure for Israel, which has prided itself on its ability to infiltrate and monitor fighters. It also exposed weaknesses in Israel's southern command.

"The communication and command of the south collapsed and there was no communication. It took time to understand the full picture," said David Tzur, a former head of Israel's Border Police force who also commanded the police's elite counter-terror unit Yamam. But the said force had now recovered.

"Once all forces are on alert there is a quick reaction."