Israel is faced with a difficult choice – initiate a ground offensive and get bogged down in urban combat against an enemy that knows the lay of the land, or continue carrying out punitive airstrikes leaving Hamas’ subterranean military infrastructure largely intact.

The October 7 raid by the Palestinian resistance group into Israel proper has forced the Netanyahu government’s hand. The Israeli Defence Forces (IDF) was not expecting to fight a possible multi-front war and was largely in a peacetime stance.

In response, Tel Aviv launched a fierce bombing campaign on the besieged enclave of Gaza and called up 360,000 reservists to shore up its peacetime force of 165,000.

Israeli options

Hamas claims to have a force of 40,000 reasonably well-trained and equipped fighters and can expect support from other groups such as the Palestinian Islamic Jihad (PIJ) which also claims a ready force of 8,000 to 10,000 fighters. As a general rule of thumb with all else being equal, an attacking force needs a 3:1 numerical advantage to attack successfully. While the Israeli forces have an overwhelming firepower advantage from their artillery and air force, their adversary has had a decade to dig in, and create tunnel networks spanning miles by some accounts and a home terrain advantage.

The IDF would be attacking into a growing rubble pile, and as previous experiences have shown in the battles of Mosul and Fallujah, rubble can just be as good to fight from as intact buildings. The attacking Israeli force will also be faced with the limited utility of its armoured forces in Gaza’s urban areas, with many avenues of attack hindered by rubble.

Hence, one option available to Tel Aviv is to mount limited incursions into the Palestinian enclave from the north – the same area they have repeatedly ordered Palestinians to evacuate. Coming in from the northern axis into an area largely devoid of civilians will enable the IDF to create a free-fire zone, where any movement can be classified as a legitimate target and neutralised through long-range firepower.

A limited operation in the north will also allow the Israelis to create a buffer zone and push Hamas rocket forces further south, enabling limited security to Israeli urban centres north of the Gaza Strip. However, a limited incursion by the IDF will not achieve the primary aim of Netanyahu’s government to “dismantle Hamas”.

The second option available to the Israelis is an invasion on a broader scale, with a possible aim of driving through and capturing the entirety of Gaza from the north to the Rafah crossing with Egypt in the south.

Again, the IDF will most likely send its main effort first into northern Gaza with another attack originating east of Gaza City near the crossing of Karni, to try and split the Palestinian enclave into two and disrupt the main road running through the enclave and Hamas’ lines of communications.

Such an offensive will present multiple challenges to an army which has largely been used for policing actions in recent years and lacks the institutional experience of fighting in dense urban terrain. But this is also the likely course of action as Israel has issued one of the largest reserve call-ups since the Yom Kippur War.

However, not all of the 360,000 reserves called up will serve in the fighting arms of infantry, armour or artillery. A large number of them will be deployed in support roles – from engineers to cooks – to support the offensive forces. Keeping the 3:1 ratio in mind, one can argue that at least 100,000 troops in fighting arms will be employed, a large number of whom will be infantry.

The Israeli ground forces will have the unenviable task of fighting through the entirety of Gaza and clearing tunnels as they move along. That will be no easy task, no army in the world has any significant experience in subterranean warfare and very few even train for such operations.

Regardless of whichever option Israel chooses, the tactical conditions will be horrendous. Israeli reservists will have to fight street to street, room to room in areas where Hamas offers resistance. How well trained those reservists will be to endure such combat conditions remains to be seen as some of the most well-trained professional armies have also struggled in similar conditions – US Marines in Fallujah.

Combat for the IDF will be slow and grinding, with Israeli war planners certainly considering operational and strategic issues as the days go by. The Israeli army will make significant use of air and artillery strikes to neutralise any resistance they face during the operation as the force is extremely casualty averse and does not have the numbers available to engage in any sort of attritional battle.

In addition to the ground offensive, the Israeli navy will be active off Gaza’s coast and can be expected to lend support to IDF forces near the coastal areas via indirect fire and intercepting and engaging Hamas’ limited naval assets which largely comprise high-speed boats and combat divers.

Hamas countermoves

The resistance group showed its ingenuity with the raid it conducted on October 7 and remains a significant threat to any Israeli advance into Gaza. Hamas does not have the capability to take the Israeli army head-on and will thus rely on classic guerrilla hit-and-run tactics, making the advance of any attacking force costly. The group also understands that it cannot win a protracted fight with Israel and will also focus on preserving its organisational structure as much as possible.

The IDF lacks significant intelligence regarding Hamas’ tunnel networks, and this can be determined from the fact that few Israeli airstrikes have targeted the group's subterranean military infrastructure and have instead concentrated on taking out urban structures deemed to be associated with Hamas. The group will use this to their advantage as it would allow it to move fighters and supplies without the threat of Israeli interdiction and help maintain combat potential. The tunnels will also give Hamas fighters the element of surprise – a key element of warfare since time immemorial.

The Palestinian resistance group is expected to have a significant defensive network comprising various firing points linked by support tunnels. Some of these defensive positions have been taken out after being identified by Israeli reconnaissance and observation assets in the ongoing aerial campaign.

During the initial stages of the invasion, some Hamas firing points will survive Israeli air and artillery attacks due to their fortified nature and such positions will be used to effectively hinder the initial Israeli advance and slow down the attacking columns or funnel them into prepared killing fields.

The majority of fighting is expected in the urban areas of the Gaza Strip as the region, unlike southern Lebanon, does not offer any significant terrain features to aid a defensive force. The lack of significant water bodies or high terrain dictates that spoiling attacks to delay an attacking force occur during the initial advance and the bulk of fighting then shifts to the towns and cities that comprise the Gaza Strip.

It remains to be seen how extensive the above-ground defence is within the urban areas, but the IDF can expect high-rises which have survived the aerial campaign to become significant strong points. Hamas will also use all other urban structures as needed and will try to channel Israeli forces into streets and thoroughfares it has prepared for the fight. The pile of rubble will also offer an advantage to the defending fighters and it remains to be seen how the Israeli forces use their armoured assets in such conditions.

A new aspect of warfare, one which Hamas has already demonstrated, is the use of commercial drones to drop munitions on troop concentrations and vehicles. First practiced by the Islamic State terrorist group during the battle of Mosul, the tactic has gained significant traction with even national armies. The Russian and Ukrainian armies have made extensive use of commercial drones, often purchased on Ali Express, to devastating effect. In a recently released video, the Palestinian resistance group also showcased locally manufactured kamikaze drones.

The use of such drones, previously unknown, by Palestinian resistance factions further complicates Israel’s planned ground invasion as it remains to be seen how effectively the Israelis can counter the new threat. A video released by Hamas on October 7 showed a commercial quadcopter drone dropping a locally manufactured warhead on an IDF Merkava tank – often touted as the best protected tank in the world – disabling it. It remains to be seen how big an inventory of such drones Hamas possesses but the threat to Israeli forces from such asymmetric means remains real.

Within urban areas, Hamas will rely on small teams to ambush and conduct guerilla attacks on Israeli forces using light arms including anti-tank rockets and improvised explosive devices.

The Levant theatre

Strategically, Israel is in a tough spot. It faces the daunting task of a land operation in Gaza while at the same time ensuring its northern border with Lebanon does not flare up. With an estimated fighting force of 100,000 Hezbollah fighters present in southern Lebanon – including battle-hardened units which fought for years in Syria – the Israeli army will be stretched if it has to engage in open hostilities on its northern border and an acute strain will be faced by IDF units engaging Hamas in Gaza. The IDF also has to contend with Hezbollah and Iran-aligned militias in Syria and Iraq which can also come into play if the conflict widens. These same groups and militias pose a significant threat to US forces in the region, with many US bases coming under attack in recent days and as confirmed by US President Biden’s recent televised remarks.

Hezbollah, following the events of October 7, drew a line in the sand by stating that any ground operation in Gaza would lead to the whole-scale involvement of the resistance movement in the current conflict. With an arsenal of more than 150,000 rockets – some with ranges in hundreds of kilometres – the Lebanese movement possesses the ability to saturate Israel’s Iron Dome missile defence system.

If recent reports are anything to go by, Tel Aviv’s stocks of Tamir interceptor missiles for its missile defence system are limited and hence, the US is returning at least two missile defence systems it purchased earlier from Israel and its stock of interceptors. However, such limited reinforcements will not offer any significant medium to long-term missile protection as Hezbollah’s missile forces have undergone modernisation since the 2006 Israel-Lebanon war and are now more potent than ever before. The group also has an arsenal of suicide drones and an electronic warfare capability which it has not revealed till now.

As part of operations to shape the battlefield in the event of large-scale hostilities against Israel, the Lebanese group has consistently targeted Israeli surveillance and intelligence bases on the border and also skirmished almost daily with Israeli troops and has knocked out an unknown number of armoured vehicles. Hezbollah can prove to be a deadly adversary for the IDF.

Israel’s closest ally, the United States, is also moving missile defence assets to the Middle East to protect its forces and those which are now being deployed to the region. Among those forces are multiple Patriot air defence batteries and a battery of THAAD (Terminal High Altitude Area Defense), its latest anti-ballistic missile defence. A fighter wing of capable F-15 aircraft has been moved to the theatre and more air units will soon reach the region.

In the eastern Mediterranean, the Ford aircraft carrier battle group is now on station near the coast of Cyprus – remaining just out of range of Hezbollah’s anti-ship missile arsenal and the Eisenhower carrier battle group is en route and is expected to be on station in the next few days. Also on station in the same area is the USS Bataan amphibious expeditionary group and its associated ships. The Bataan carries a complement of US Marines and a large number of helicopters. The ship can be used to either land US troops to support Tel Aviv’s combat operations or evacuate US civilians from the conflict zone and is a capable asset.

It can be expected that if Israel goes for occupation of Gaza, it would need to station a substantial number of troops in the occupied territory to conduct intensive counter-insurgency operations. The general rule is a ratio of 1:20 of security personnel to local inhabitants. An occupation army of around 100,000 would be required to keep Gaza’s 2.2 million inhabitants subdued, given that they hate Israelis to an extent that Western policy makers have difficulty in understanding. This mission would require doubling the standing strength of the peacetime Israeli army from reserves, and keeping them deployed for years to come after a grueling urban battle. There is no easy way out for Israel in the current scenario.

Israel has continuously delayed its invasion of the Gaza Strip, starting with the initial excuse of inclement weather in the region to now stating that the US has asked it to delay the offensive to ensure all American defence assets are in position in case the conflict spreads beyond the immediate region. It remains to be seen when the IDF surges forth into Gaza, but whenever the moment arrives, it will be involved in combat operations the scale of which has not been witnessed since 1973.