In the 18 years since withdrawing from the Gaza strip, Israel has invaded it twice.
The first occasion was Operation Cast Lead, which involved a 15-day ground invasion in January 2009.
The second was Operation Protective Edge in 2014, in which the Israel Defence Forces (idf) spent 19 days on the ground.
A third ground invasion, in response to the massacre of Israeli civilians by Hamas, the Palestinian militant group that runs Gaza, is imminent. It looks likely to be larger, longer and more violent than anything that came before.
Air strikes and artillery, including missiles launched from land and sea, are already pounding Gaza. This is taking place on a massive scale and with less deliberation and advance warning than in previous campaigns.
Israeli officials say that the IDF is no longer applying its policy of “roof knocks”, whereby the air force would give warning of air strikes by first launching a harmless round on the targeted building. At least 900 Palestinians, many of them civilians, have so far been killed, according to the Palestinian health ministry in Gaza.
Israeli political leaders are now considering the scope of their ground offensive.
One option is a shallow incursion of the sort which occurred in 2014, when the idf captured territory adjacent to the border with the aim of closing tunnels used to smuggle food, fighters and arms. It stuck to the outskirts of main towns to avoid urban warfare. Another is a deeper invasion to occupy larger tracts of the Gaza strip, a densely packed area of more than 2m people, including entering cities, as in 2009. Yet these past approaches may seem inadequate to Israelis given the widespread revulsion at Hamas’s atrocities.
“The scope of this is going to be bigger than before and more severe. It’s not going to be clean…We are going to go very, very aggressively against Hamas,” Israel’s military spokesman, Richard Hecht, told reporters on Tuesday morning. “We should all change the paradigm.” Israeli leaders have promised to “destroy Hamas”, rather than simply weaken it, as in the past.
“The era of reasoning with these savages is over,” declared Gilad Eran, Israel’s envoy to the United Nations. “Now is the time to obliterate Hamas terror infrastructure, to completely erase it, so that such horrors are never committed again.”
News of a gruesome massacre in Kfar Aza, a southern kibbutz, has hardened the mood. Some have hinted at collective punishment. “Hamas became ISIS and the citizens of Gaza are celebrating instead of being horrified,” said an Israeli general. “Human beasts are dealt with accordingly.”
Hamas, notes Daniel Byman of Georgetown University, is deeply rooted in Gaza, embedded in a range of charities, schools and mosques. “Separating Hamas from Gaza is an almost impossible task,” he says. A re-occupation of Gaza is implausible. Israel left it in 2005 in part because it was so costly to hold.
In the West Bank, notes Mr Byman, Israel uses the Palestinian Authority, Hamas’s rival, as a sort of auxiliary force. That is not an option in Gaza. Using Israeli troops would bog down a large proportion of the IDF leaving it short-staffed in the restive West Bank. “The last thing Israeli politicians would want would be a steady drip-drip of casualties from Gaza, where every week there’s more Israeli death.”
An alternative approach would be a larger version of Cast Lead. The IDF is not yet ready for that. It has mobilised 360,000 reservists, almost as many as during the Yom Kippur war of 1973. However, many of these troops are not combat soldiers but ballast for intelligence units, air-force squadrons and logistics units.
The IDF is likely to deploy two armoured divisions and one lighter airborne division, each of which has five brigades. Some of these units are waiting for their tanks and other armour to reach staging areas around Gaza. Others took losses over the last several days of combat with Hamas.
If Israeli leaders eventually order a large-scale invasion, one or two armoured brigades with tanks would probably push 6km west to the coast either north or south of Deir al-Balah, a central city, to cut Gaza in two. Two or three other brigade-sized units—a few thousand men each—would probably focus on the north, including around Gaza city, and one or two others on Khan Yunis or Rafah in the south.
Their aim would probably be to target Hamas and Palestinian Islamic Jihad (pij), a separate militant group close to Iran, focusing on leaders and infrastructure that could not be struck from the air, or where doing so would entail particularly high civilian casualties.
Hamas has several hundred kilometres of tunnels in Gaza. Locating their entrances and dropping in explosives will be a priority. The biggest challenge will be urban warfare, a notoriously messy business.
In 2014 Hamas used small but heavily armed assault squads, equipped with machine guns, anti-tank guided missiles and grenades, and sometimes wearing idf uniforms, to inflict casualties on even the best Israeli and armoured formations, according to a study by the Rand Corporation, a think-tank. “Resistance to Israeli ground forces was skillful, adaptive and conducted coherently,” notes the study. “Personnel were willing to engage in close combat with Israeli forces and conducted infiltration and ambush missions with determination.”
Much will depend on which of Israel or Hamas has learnt more effectively from that previous round of fighting. The IDF will take heart from its recent experience in the West Bank.
In July two small brigade teams of 1,000 men in total, without tanks or infantry fighting vehicles, entered the town of Jenin for 48 hours, destroyed dozens of buildings used by Hamas and pij and killed 12 Palestinians, nearly all of whom were thought to be militants. The idf lost only two soldiers. Its job will also be made easier in Gaza because Hamas lost over 1,500 men during its raid; those are likely to have included many of its most motivated fighters.
Israel’s success in Jenin was achieved mainly through diligent planning, good intelligence, quick movement and constant drone coverage. The latter will be impossible to replicate in Gaza, given the sheer number of drones that would be required for blanket coverage, but the idf might choose to work in stages, focusing on a few neighbourhoods at a time.
Drones will be even more crucial in this campaign because the massive array of ground-based cameras and sensors around Gaza was decimated during Hamas’s raid. Colonel Roi Levy, the head of the idf’s elite “Ghost” unit, a highly specialised and secretive reconnaissance outfit designed to find hidden objects, was also killed on October 7th.
A massive invasion will face several constraints, apart from delays in assembling the force. Israeli casualties could be severe, potentially pushing the idf to employ more firepower. “I think it’ll be willing to inflict a lot of casualties,” says Mr Byman, “both to restore deterrence, but also to protect its forces.”
The idf will also have to guard its northern border in case Hizbullah, a powerful Lebanese militant group, joins the fray. Towns in northern Israel have been evacuated. Late on October 10th Israel also responded to attacks from Syria with artillery fire.
A further complication is the presence of over 100 Israeli and foreign hostages in Gaza. Hamas has threatened to execute one each time Israel strikes civilian homes “without advanced warning”. Bezalel Smotrich, Israel’s far-right finance minister, has called for the idf to “not take the matter of the captives into significant consideration.” The idf will use special forces to find and rescue hostages if it can, but Hamas is likely to have dispersed them over a wide area, including underground.
On October 10th Joe Biden, America’s president, offered strident support for Israel, promising military aid, some of which has already been sent. Israel has asked for precision-guided munitions and interceptors for its Iron Dome missile-defence system, both of which might run short in a prolonged war.
British, French, German and Italian leaders have also offered their support. But a backlash from Arab states is inevitable, potentially jeopardising Israel’s effort to normalise ties with Saudi Arabia, a process which had been accelerating in recent weeks.
Ultimately, Israeli leaders are caught between the maximalist rhetoric of eliminating Hamas and the implausibility of re-occupying Gaza. Hamas leaders and a large proportion of fighters are likely to emerge from their bunkers and restore control over the strip the minute the idf leaves. Even if Israel were to succeed in smashing the group, it is unclear to whom Israel would then turn to administer the territory.
During his long career in Israeli politics, Binyamin Netanyahu, Israel’s prime minister, has been cautious in using military force, despite his public hawkishness.
Yet the trauma of October 7th—which Isaac Herzog, Israel’s president, described as the bloodiest day for Jews since the Holocaust—may have a profound effect. “The Israeli willingness to bear—and exact—costs is much higher than in the past,” says Natan Sachs of the Brookings Institution, a think-tank in Washington. “Just as the US would do things on 9/12 it wouldn’t have dreamed of doing on 9/10…so Israel is very different than the Israel of 10/6.”