Urban combat and underground war: What to expect from Israel's ground operation in Gaza

RU

Setting the landscape for the Battle of Gaza

On October 7, when Israeli settlements bordering the Gaza Strip were attacked by militants, the IDF launched Operation Swords of Iron. The first stage focused on regaining control over the territories outside Gaza, destroying the militants who had infiltrated Israel and dispersed over a large area, and securing the demarcation line to prevent new infiltrations.

In the meantime, so-called “shaping operations” were carried out – preparatory activities that laid the groundwork for the future offensive. Normally, the key stage of shaping operations is the isolation of the combat zone by physically disrupting the logistics systems that allow the movement of people and goods. But the Gaza Strip has already been isolated since 2007, by both Israel and Egypt.

An integral part of the ongoing preparation is the continuous missile and bombing strikes, carried out both from the air and from the surface. The current campaign is marked by extreme intensity, with 6,000 bombs dropped on the Gaza Strip in six days and 3,600 targets hit (mostly in the northern part of the exclave). By comparison, in the anti-ISIL operation of 2014–2019, the U.S.-led international coalition fired 2,000 to 5,000 airborne munitions a month against targets in Syria and Iraq.

The Israeli Air Force is conducting its campaign against a predetermined bank of targets at an exceptionally high pace, which is explained, among other things, by the desire to inflict as much damage as possible before the suffering of civilians in the Gaza Strip results in considerable international pressure. There is, of course, legitimate doubt that the IDF had 3,600 predetermined targets, given that the total number of Gaza’s armed forces does not exceed 30,000 troops (see below).

Long-range strikes solve several problems at once.

Firstly, they destroy the “vertical” landscape featuring high-rise buildings, which can each be turned into a defense stronghold or launching pad for rockets fired into Israeli territory. The IDF has released footage of rocket launchers firing directly from residential buildings in the middle of an urban neighborhood. Turning the Gaza Strip into a more “horizontal” space would certainly help in a ground invasion.

Secondly, they hit command posts, communication points, places where personnel are stationed, and ammunition depots, although there are certain challenges because Hamas keeps most such facilities underground, in an extensive system of tunnels and embedded structures.

Thirdly, they can eliminate the commanders of enemy security forces, thus disorganizing the enemy’s defense activities. The IDF reported eliminating several high-ranking Hamas commanders: Abu Merad, the head of its air force (which consists of paragliders and paratroopers who make landings in Israel); Ali Qahdi, the head of the Nukhba commando unit; Bilal al-Qedr, the commander of a company within Nukhba, which was responsible for the attacks on Kibbutzim Nirim and Nir Oz, and several other prominent terrorists.

Finally, the IDF’s crucial task is to clear the area of its future ground operation of civilians. Israel declared a complete blockade of the Strip, cutting off supplies of water, electricity, fuel, and food (however, water supplies to southern Gaza were later restored under U.S. pressure). The Israeli command has identified an area in the northern Gaza Strip from which residents have been advised to evacuate to the south.

Humanitarian law issues are already at the forefront of the conflict, and the displacement of so many people (up to a million by some estimates) in a short period is the epitome of a humanitarian disaster and has already triggered a protest from the UN. Hamas complicates the matter by urging civilians to stay in their homes and impeding their evacuation with road barriers.

In addition, despite the efforts of the U.S. government, civilians still can't leave the Gaza Strip: Egypt, the only country besides Israel that has a land border with the Palestinian territory, refuses to accept refugees, citing its reluctance to contribute to what it sees as de-facto eviction of the Arab population. Since the start of the current escalation of the Israeli-Palestinian conflict, Egyptian authorities have erected concrete barriers at the Rafah Border Crossing.

The battleground: dense development and underground tunnels

The Gaza Strip is a very small territory (360 square kilometers) with a population of 2 to 3 million people, according to various estimates, half of whom are under the age of 18. It's one of the most densely populated places in the world. However, it is a mistake to think of the Gaza Strip as one big city: there are several separate settlements, and Gaza City proper is only one of them. Nevertheless, the Israelis are in any case looking at what is known as urban warfare – fighting in a city environment.

As discussed above, Hamas' military infrastructure is mostly located underground rather than on the surface. In fact, the entire Gaza Strip consists of two “layers”: “upper Gaza” and “lower Gaza.” The underground layer, which consists of tunnels and bunkers, is a real “terra incognita.” The infamous “Gaza Metro” has enjoyed colossal investment: according to some sources, up to 95% of cement supplies to the Gaza Strip were used for capital military construction. The tunnels are up to 30 meters deep and are believed to feature autonomous life support systems and even rail tracks.

“Metro” is an apt term: if we were to believe Hamas representatives, the underground network is about 500 kilometers long – to compare, the London Underground is only 400 kilometers long. The core part of the “Gaza Metro” is in the north of the Strip, in the area the IDF has declared unsafe for civilians.

Most likely, all assets of value to Hamas (not only ammunition, command and control centers, but also hostages) are being kept underground. In a sense, this is an undoubted tactical advantage, since the IDF only possesses a limited number of anti-bunker bombs (e.g., just around 100 American GBU-28 bombs), and it is tricky to destroy the tunnel network with other types of munitions. However, this is where U.S. supplies could come in handy, and it should be noted that they barely overlap with Ukraine's needs.

Hamas has also been using simpler, non-reinforced tunnels for its attacks. In 2006, one such tunnel was used in an attack on an Israeli roadblock, during which the militants captured Corporal Gilad Shalit. After that, Israel began the construction of underground barriers on the border with the Gaza Strip and put in place a high-tech system of detectors and sensors by leading defense enterprises Elbit Systems and Rafael Advanced Defense Systems. The Israelis spent about $1 billion on these defenses, but the construction of tunnels is not cheap either: according to Israeli estimates, each costs Hamas $3 million.

The parties' forces and means

Israel called up 360,000 reservists in a matter of days, bringing the total number of its armed forces to half a million troops. Reservists immediately began reporting issues with equipment and supplies. Although IDF officials deny logistical challenges, volunteers are currently responsible for equipping the reservists at least partially. It is unlikely, however, that all of the drafted Israelis will take part in the ground operation.

Equipment and military personnel are now accumulating on the borders of the Gaza Strip, and their concentration is such that outside observers are accusing the IDF of completely disregarding the lessons of the war in Ukraine. But since the enemy has so far failed to take advantage of the densely positioned enemy troops, we can conclude that Hamas forces do not have long-range precision weapons capable of overcoming Israeli air defense and EW assets, including loitering munitions of the required parameters.

As for fighting in city streets, Israel has one of the largest urban warfare training centers in the world (the Tze'elim Base, which features a replica of a typical Middle Eastern city), and a large fleet of specialized engineering equipment, such as the D9R, a huge armored bulldozer with a machine gun.

The IDF also has an overwhelming air superiority, but it is unclear how freely Army and tactical aviation will be able to operate. Hamas militants have shown off “original” surface-to-air rocket launchers (however, experts have questioned their effectiveness). Four Israeli helicopters were reported downed, but only one CH-53 transport helicopter has been reliably lost so far, and it was on the ground.

At that, we can't ignore that even before the start of its ground operation, the IDF suffered immense losses by its standards. According to the latest available reports, 291 soldiers were killed – more than in any conflict involving Israel since the first Lebanon War (1982–1985).

Equipment losses are estimated at 127 vehicles: 20 destroyed, 100 captured, and 7 damaged. However, local Islamist militias are unlikely to have transported hardly any of the “captured” vehicles (especially tracked ones) to the Gaza Strip and never began using them in combat (as for wheeled vehicles, at least some of them were eventually evacuated).

In terms of forces in the Gaza Strip, apart from Hamas fighting units, there are their allies from other movements, notably the Palestinian Islamic Jihad, the Popular Resistance Committees, the left-wing Popular Front for the Liberation of Palestine, and even the Marxist-Leninist Democratic Front for the Liberation of Palestine.

The total strength of the Izz ad-Din al-Qassam Brigades (the militant wing of Hamas) is estimated at 15,000-20,000 troops, and the al-Quds Brigades (the militant wing of Palestinian Islamic Jihad) are believed to have 6,000 troops. Together with all the allies, it is unlikely to get more than 30,000 troops – and this is light infantry without heavy armored vehicles or field artillery. What they should have in abundance is rockets.

Israeli intelligence estimates for 2021 indicate a stockpile of some 30,000 rockets in the Gaza Strip. This includes not only smuggled supplies but also local production almost from scratch. Footage of Palestinian fighters digging up a water pipeline financed with EU funds and using the pipes for rocket casings describes Hamas’ military “industry” quite eloquently. By today, they have used over 6,000 rockets from their arsenal. A certain quantity has probably been destroyed in the air strikes, but the majority probably remain intact in underground depots.

Possible scenarios: urban warfare, subterranean warfare, and “The Siege of Leningrad”

The New York Times wrote that the ground operation was already supposed to have begun but had to be postponed due to weather conditions, which probably speaks to the importance of aerial reconnaissance and full air control of the Gaza Strip for the Israeli General Staff. The IDF is already carrying out localized raids in parts of the exclave but seems to need another several days or even weeks to prepare for a full-scale operation. So far, IDF raids have focused on retrieving the bodies of Israeli hostages spotted from the air, either killed in captivity or taken to Gaza already dead.

The key issue is the targeting – and therefore the format – of the ground operation. Since its full withdrawal from the Gaza Strip in 2005, Israel has conducted ten military operations against local militants, but only half of them included a ground component:

• Operation Summer Rains from June 28 to November 26, 2006. Objective: locate and release kidnapped Israeli Corporal Gilad Shalit. Israel’s combat losses: five killed, 38 wounded. The operation featured a land phase.
• Operation Autumn Clouds, November 1–26, 2006. Objective: destroy rocket launchers firing rockets into Israeli territory. Israel’s combat losses: one killed, three wounded. The operation featured a land phase.
• Operation Hot Winter from February 28 to March 3, 2008. Objective: destroy rocket launchers firing rockets into Israeli territory. Israel’s combat losses: three killed, 8 wounded. The operation featured a land phase.
• Operation Cast Lead from December 27, 2008, to January 18, 2009. Objective: destroy rocket launchers firing rockets into Israeli territory. Israel’s combat losses: 10 killed, 336 wounded. The operation featured a land phase.
• Operation Pillar of Defense, November 14–21, 2012. Objective: destroy rocket launchers firing rockets into Israeli territory. Israel’s combat losses: two killed, 20 wounded. No land phase.
• Operation Protective Edge from July 8 to August 26, 2014. Objective: respond to the riots in the West Bank and destroy rocket launchers firing rockets into Israeli territory. Israel’s combat losses: 66 killed, 469 wounded. The operation featured a land phase.
• Operation Black Belt, November 12–14, 2019. Objective: destroy rocket launchers firing rockets into Israeli territory. Israel's combat losses: none. No land phase.
• Operation Guardian of the Walls, May 10–21, 2021. Objective: destroy rocket launchers firing rockets into Israeli territory and underground tunnels. Israel’s combat losses: one killed, three wounded. No land phase.
• Operation Breaking Dawn, August 5-7, 2022. Objective: destroy rocket launchers firing rockets into Israeli territory. Israel’s combat losses: two wounded. No land phase.
• Operation Shield and Arrow, May 9–13, 2023. Objective: destroy rocket launchers firing rockets into Israeli territory. Israel's combat losses: none. No land phase.

The last time the Israeli military fought on land in the Gaza Strip was in 2014; since then, local Islamists have significantly increased their combat capabilities. In all of the listed operations, both the objectives and the forces involved were quite limited. Today, if the Israeli leadership is truly determined to wipe out the terrorist threat from Hamas once and for all, most experts agree that a full occupation of the exclave is unavoidable.

A ground operation in the densely populated Gaza Strip appears highly challenging. Urban warfare is the most destructive kind of combat, as seen in examples such as Fallujah (Iraq, 2004) and Mariupol (Ukraine, 2022).

Even if all the buildings in the area are leveled, battles can still be waged amid the ruins. This might involve setting up traps, mining certain areas, deploying snipers, or employing other tactics. Given the Hamas militants’ success in carrying out their offensive, it is likely that the group will mount a challenging defense. This will place greater demands on tasks like engineering reconnaissance, coordinating forces during battles, and using more ammunition.

By some estimates, urban warfare requires four times more ammunition than fighting in other environments. Observers of the Russia-Ukraine war remember Wagner Group co-founder Yevgeny Prigozhin’s constant complaints about the lack of ammunition during the storm of Bakhmut. According to one of the group's mercenaries, the PMC preferred to destroy AFU strongholds with artillery fire, but the lack of ammunition gave it no choice but to launch unprepared assaults, which led to significant casualties.

In a ground operation, dealing with underground tunnels becomes a pivotal challenge. This might necessitate what's known as Subterranean Warfare, where battles take place beneath the surface. Israeli forces may lack a comprehensive understanding of the structure and functionality of the underground network of tunnels in Gaza, potentially allowing Hamas fighters to maneuver their reserves right beneath advancing forces and launch sudden attacks from the rear. Managing this situation could require a substantial deployment of tens or hundreds of thousands of soldiers to gain full control of the area above ground. Occupying the tunnels would likely demand not only well-trained soldiers but also remotely controlled equipment to minimize the risk of personnel getting trapped.

Somewhat ironically, Jews were among the first to use underground spaces for guerrilla warfare against Roman legionnaires in the first century A.D. Sewer tunnels were also used during the Warsaw Uprising in 1944 to communicate, supply and evacuate areas where further defense was impossible. During the battle for Mosul in 2017, ISIS militants also used underground tunnels very successfully, and the battle dragged on for 9 months, with almost the entire city having to be destroyed.

Drones are the next challenge. Hamas, along with its allies, has already shown that it is very effective in using them for reconnaissance and as strike weapons. In urban areas, drones can be a very effective tool for coordination and strikes against heavy equipment. However, judging by recent photos, the Israeli military — at least at the grassroots level — is still adopting the experience of the Russian-Ukrainian war by installing anti-drone cages (commonly referred to as «cope cages») on tank turrets. It's worth noting that this particular design creates fewer problems for the crew during rapid evacuation, especially in comparison to Soviet and Russian tanks, thanks to a rear hatch in the Merkava tank's hull.

Perhaps the most challenging will be the presence of civilians. Some of them will probably be used by the militants themselves as human shields; some of them will simply be unable or unwilling to leave their homes, inadvertently staying the war zone; some of them will take up arms to avenge their relatives and friends killed in Israeli bombardments or will become suicide bombers. If a substantial portion of Gaza Strip residents remain in the area, the IDF might be forced to conduct limited operations, using the blockade to put pressure on the Hamas leadership. Russian President Vladimir Putin, in trademark fashion, compared these tactics to the siege of Leningrad.

The combination of these factors is likely to lead to substantial military losses for the IDF and a tragically high number of civilian casualties in the Gaza Strip. The former is bound to become a political issue within Israel, as the Israeli society is highly sensitive to military casualties, and the latter will result in increased international pressure on the Israeli political leadership.

How exactly the ground operation will unfold primarily depends on the objectives. For instance, Prime Minister Benjamin Netanyahu's speeches have repeatedly stated the goal of destroying Hamas. While there have been calls among Israelis to extradite these leaders or even consider a military operation to neutralize them, it is hardly possible to physically eliminate or detain all participants or supporters of the movement within the Gaza Strip.

That said, it’s difficult to say what will happen after a military victory. Obviously, Israel cannot afford to remain in Gaza permanently, nor can it withdraw, because Islamist forces, probably even more radicalized, will return to power and again begin building the capacity to attack Israel. The experience of the territories Israel has occupied in the past and later withdrawn from (the Sinai Peninsula, South Lebanon and Gaza) clearly shows that there are immediate security threats there.

What can be said with absolute certainty is that the duration of the operation must be limited in time. For purely economic reasons, it will not be possible to wage war for a long time: 360,000 people have been drafted, and it is very difficult to keep them at the front even for a few months. Preliminary estimates of the cost of the war against Hamas place it at around $7 billion.

David Sharp, Israeli military expert: “We have to assume the worst-case scenario, which is that they will mount a long and determined defense”

“Unlike the ground operations that took place in decades past, the primary objective in this situation is significantly broader: the complete dismantling of Hamas military forces and infrastructure throughout Gaza. To put it more plainly, the goal is to gain full control of the Gaza Strip. Only in that way can Hamas be decisively defeated and the movement destroyed. Preparations for such an operation have been ongoing, with operational plans in place for a long time. Naturally, they must be adjusted depending on the situation.

Many problems await us. This is a complex operation. Of course, everything depends on the level of the enemy's resistance. I assume that at some stages it will be strong — it may even be quite formidable. We have to assume the worst-case scenario, which is that they will mount a long and determined defense. Gaza covers 365 square kilometers, most of it is built-up, the construction is very dense, one of the densest in the world — that includes half-meter distances between houses and between walls in some places. These areas are not like the usual urban neighborhoods in modern cities, although some are. Fighting in these conditions is tough by its very nature.

Hamas and Islamic Jihad are the strongest terrorist organizations in [the Gaza Strip]. There are different data on who to count, but let's assume that Hamas has about 40,000 militants. These structures may have different purposes, but in general they are disciplined military or police-type militias with their own commanders and areas of responsibility.

They've been preparing to defend themselves for many years, learning from their mistakes and training in Iran, Lebanon and [in Gaza]. They’re quite well-armed — [they have] small arms of any type up to sniper rifles, large-caliber machine guns, rifles, automatic rifles, the mass use of booby traps, RPGs, guided anti-tank missiles including the Russian Kornet, mortars from 82 mm to 120 mm. All of this can and will be used [in the defense of Gaza].

Another problem is the tunnels. Under Gaza, there are extensive defensive tunnels that span for dozens of kilometers. In the Israeli military, we call offensive tunnels as those dug under the border fence for infiltration into Israeli territory, while defensive tunnels are used during Israeli ground operations. These tunnels serve various purposes, including discreet movement between locations and houses to avoid aerial reconnaissance. Some of these tunnels are also used for launching rockets, with the rocket launcher sticking out from the inside. These tunnels can be used to outflank Israeli positions, and tunnel branches can be rigged to act as a huge mines. In general, tunnels are a key advantage — they even had a major underground city at one point. During the last operation, a noticeable portion of these tunnels was targeted and destroyed. However, it's likely that they've rebuilt most of them if they chose to do so, given the time they've had.

Warfare in a built-up area is a tricky business. The deployment of heavy equipment can be limited in such environments, and the presence of civilians adds another layer of complexity. Israel acknowledges the presence of human shields,” and navigating through the intricacies of built-up areas can be challenging. The enemy has prepared defenses that include tunnels, booby traps, and mined buildings. [The Israeli army will face] a lot of things, but everyone understands that perfectly well, as [Israeli military] intelligence has been working to study Hamas' capabilities. Naturally, there will be mistakes, there will be casualties and there will be pain, but there is no other way out.

If it were possible to employ 17th-century tactics today, this issue could be resolved quite simply — essentially blockading Gaza completely, disregarding humanitarian concerns and the Geneva Convention, and using artillery to indiscriminately bombard residential buildings, causing mass casualties. These ancient methods would likely lead to [the local population] bringing out the severed heads of their leaders, — however, this is all nonsense, as this line of thinking is unrealistic in modern times and is not an acceptable course of action. As for high-precision strikes with modern weaponry — Israel has been doing that for years. That's not how problems are solved. Modern aviation doesn't drop bombs without discretion, aiming to kill thousands.

If destroying Hamas in the Gaza Strip as an organization wasn't on today's agenda, exchanging blows as before would be possible. In the past, [Israel] even launches partial ground assaults, fired at someone, they fired rockets back, and that's how it ended. Only victory should be on the agenda today, not an exchange of blows. It is necessary for those who made the decision to massacre and their subordinates and formations to cease to exist. This is the only way to at least partially make up for what has happened and change reality. A reality where there is this adversary who is capable of such steps, who has such an opportunity and who is right next door - this is unacceptable.

Another very important point — other players in our region who are stronger than Hamas, such as Hezbollah, Syria and Iran, must learn a lesson. Yes, Israel's military and security forces failed, and the consequence was a horrific tragedy, but they must realize that Israel has the strength and motivation, and it is more costly to do the same to Israel. This should also be a lesson to others, because otherwise they will become bolder. They are already getting bolder, largely due to Israel's perceived lack of a decisive response in recent times.

I think Hamas was confident that Israel would eventually not dare deal it a lethal blow in Gaza. Otherwise, they would have been unlikely to go for such [an attack]. Either way, the enemy that perpetrated it needs to be destroyed, and a lesson needs to be taught to others. Without a ground operation, this can only be solved by medieval methods. At the moment, Hamas has won on its own terms — both in its own eyes and in the eyes of the Arab street. And they have won a crushing victory. To kill so many Israelis and military personnel, to take so many people captive, and to embarrass the Israeli army in such a way — this is something the Arabs have dreamed of for decades. [Israel] needs to make this not a victory, but the first act of a suicidal move [for Hamas]. That is why I see the need for a ground operation with far-reaching objectives. The guns will do the talking from now on.”

David Gendelman, Israeli military expert: “A complete takeover and sweep of Gaza would require at least four divisions and multiple weeks”

“Again, we have to stress that there is no official announcement of a ground operation in Gaza yet, but forces have been pulled in and preparations are basically more or less complete. How do we see this operation? It depends on the goal that will be set for the army and on the specific orders, as there are several operational plans at several levels, up to a full takeover and a complete sweep of the Gaza Strip. If we theoretically take the option of a full takeover and clean-up, this would indicate required combat and numerical strength of four divisions at a minimum, with the estimated time frame for a takeover at a few weeks, according to the plans, then a few weeks for the sweep.

One has to look at the enemy. Hamas has built a powerful defense system over the years of its rule in Gaza, which includes not only ground fortifications, but also a whole underground city — that is, a network of underground tunnels that is used both for the movement of militants and for underground headquarters, command and control points, surveillance, ammunition depots and other things. They can live there autonomously for a long time and pop out for battle at the right time. This adds to the complexity of the situation, alongside the customary factors in play: mined tank-hazardous areas, mine traps, combined engineering barriers, ambushes with pre-equipped hidden firing points, above-ground and underground, plus surveillance equipment, mortars, ATGMs, MANPADS, UAVs, and so on.

[Hamas] also a large rocket arsenal, but it is mainly for firing at Israel — not for fighting in Gaza. All in all, there are up to 40,000 Hamas fighters there, up to 15,000 Islamic Jihad militants, several thousand more fighters from other paramilitary groups, and [Israel] needs to act against all of them put together. The operational plans for all of this are in place. As usual, they're assault operations in built-up areas. Understandably, it's not going to be easy. The estimated losses of the Israeli army will be several hundred people.

The Gaza Strip covers an area of 365 square kilometers and is home to 2 million people. Even if you were to divide and clear the area bit by bit, it remains a formidable challenge, particularly due to the presence of an extensive underground city. The Israeli military has specialized units for subterranean warfare, but it's evident that the environment makes it a challenging task. Nevertheless, challenging doesn't mean impossible. The question is which orders the government will give — the army will execute them regardless.

If the objective is to destroy Hamas, it cannot be done from the air alone. While [airstrikes] can cause significant damage, they can't fully destroy the extensive underground infrastructure — unless nuclear weapons are used or the entire ground level of Gaza is completely wiped out. We've seen this many times in past rounds of escalation against Gaza. Yes, powerful strikes do a lot of damage to military and other capabilities, but there's a political aspect here as well — Israeli society now demands a dignified and powerful response to what has happened. Many may look on the lack of a ground operation negatively, despite the losses, because it'll look like we didn't go to a full-fledged war and are still holding back, no matter what.

So again we come back to what goal the government will set for the army. Even if such a decision has been made, it has not been officially voiced. Only the vague wording about a powerful blow to Hamas's military capabilities has been said aloud. All the other formulations about how Gaza will 'remember this for 50 years' and 'we'll change the Middle East' are all very abstract. So let's look at the real orders and real actions.”