If Israel launches a ground campaign into Gaza to clear the dense areas of Hamas military capability—and all indications are that it intends to—Israeli forces can expect to face a wide range of challenges. Some of these are common features of modern urban warfare history, while others stem from the unique characteristics of Gaza’s urban terrain. But one challenge spans both categories: tunnels. Subterranean spaces have featured in other urban battles—not only recently but stretching back to ancient history. But the scale of the challenge in Gaza, where hundreds of miles of tunnels crisscross below ground in the enclave, is entirely unique. This expansive underground complex is the wicked problem—one for which no perfect solution exists—awaiting Israeli ground forces.
Tunnel warfare is not new. From medieval mining and countermining, its long history extends through the subterranean component of the World War I battles of the Somme, Vimy Ridge, and Messines to the deep natural and manmade tunnels used at Mariupol, Bakhmut, and Soledar during the ongoing war in Ukraine. The US military’s experience with tunnels includes the Civil War sieges of Vicksburg, Mississippi in 1863 and Petersburg, Virginia in 1864, the massive underground complexes of the Vietnam War, and both to al-Qaeda and ISIS tunnels in Afghanistan, Syria, and Iraq. In Vietnam, where North Vietnamese and Viet Cong forces used miles of tunnel networks to protect their supply routes, military forces, and bases in places like Cu Chi, the problem became so severe that it forced the development of new tactics such as sending soldiers, called tunnel rats, into tunnels armed with only a pistol and flashlight.
The Israel Defense Forces (IDF) are very aware of the presence of Hamas tunnels in Gaza. They often refer to the group’s tunnel systems as the “metro.” The destruction of these tunnel complexes was one of the objectives of previous ground campaigns into Gaza, in 2008 and 2014. In total, there were believed to be over three hundred miles of tunnels in 2021, when Israel claimed to have destroyed sixty miles of tunnels during an eleven-day bombing campaign. Even if those tunnels have not been rebuilt or replaced, that means that it is likely that there remain hundreds of miles of intricate, complex, and deep tunnel infrastructure in Gaza. It is a veritable city underneath the cities on Gaza’s surface.
In the event of a ground campaign launched by Israel, Hamas would use its tunnels both defensively and offensively. The way it employed these spaces against the IDF during Israel’s 2014 Operation Protective Edge offers clues about what to expect in the days and weeks ahead.
Defensively, Hamas will use tunnels to escape IDF observation and attack. Any Hamas military capability that survives Israel’s current air campaign will mostly be deep underground. Hamas will have already placed its leadership, fighters, headquarters, communication, weapons, and supplies like water, food, ammunition in its tunnel complexes to prepare for the ground assault by Israeli forces. The tunnels will allow fighters to move between a series of fighting positions safely and freely under massive buildings, even after the IDF drop thousand-pound bombs on them. Hamas tunnels often have generator power, air ventilation, water pipes, and stockpiles of food that will allow the group’s fighters to better withstand the most basic challenges, like normal exhaustion, that result from urban siege and isolation. Hamas leaders and fighters will use the tunnels to remain mobile to escape entire sections of the combat area when they feel they are about to be decisively attacked or surrounded. Importantly, Hamas has also dug a large portion of its tunnels under, and connected to, civilian sites like school, hospitals, and mosques in dense urban areas. Among other reasons for doing so, this is part of its defensive lawfare strategy.
Offensively, Hamas tunnels allow the group’s forces to conduct protected and surprise attacks. They will use the tunnels to infiltrate behind IDF positions to surprise Israeli forces that might not be as well prepared or equipped for combat as those spearheading the campaign, like those in logistical areas. Interconnected tunnels under urban areas will allow Hamas to move quickly between prepared attack positions with caches of sniper rifles, antitank munitions, rifle-propelled grenades, and other weapons and ammunition. Tunnels will be the vital element of Hamas’s guerrilla warfare strategy. Its fighters will form small hunter-killer teams that move underground, pop up, strike, and pop quickly back into a tunnel. Hamas also uses the tunnels to hide and move rockets. These rockets can be remotely detonated or transported to hidden launch sites at the last minute. Hamas will also have many tunnels rigged with hundreds of pounds of explosive to function as tunnel bombs under main roads and buildings that the IDF might be lured into.
Entering tunnels presents unique tactical challenges, many of which cannot be addressed without specialized equipment. In some cases, it can be impossible to breathe without oxygen tanks in tunnels, depending on their depth and air ventilation. It can also be impossible simply to see. Most military night-vision goggles rely on some ambient light and cannot function when it is entirely absent. Any military navigation and communication equipment that relies on satellite or line-of-sight signals will not work underground. A weapon fired in compact spaces of tunnels, even a rifle, can produce a concussive effect that can physically harm the firer. A single defender can hold a narrow tunnel against a much superior force.
Of course, not all military tunnels and bunkers are the same. I have seen firsthand the wide variety, having been in North Korean invasion tunnels discovered in South Korea, Iraqi military bunkers, defensive bunkers and tunnels in Nagorno-Karabakh, and Hezbollah tunnels along the Israeli-Lebanese border. Two features typical of Hamas tunnels are important to note. First, Hamas tunnels are almost all very narrow, largely because of the prefabricated concrete sides and tops Hamas favors to build them. The average Hamas tunnel is just two meters high and a meter wide, making entering, moving through, fighting in them extremely hard. Second, because of Israel’s advancements tunnel detection and destruction, Hamas has dug its tunnels deeper and deeper. In 2020, Israel found a Hamas tunnel that descended 230 feet below the surface, the deepest found up to that point.
On the other side of the equation, there are a number of particular capabilities available to the IDF to deal with the challenge of Hamas tunnels. I have studied the phenomenon of subterranean warfare in conflicts around the world, have worked with leading scholars and experienced military practitioners to better understand its role in urban warfare, and am a founding member of first and only International Working Group on Subterranean Warfare. Of all the forces I have studied, the IDF has done the most work to prepare for dealing with tunnels in war.
The IDF has the capability to find, recover hostages from, clear, neutralize, and destroy tunnels. There are specialized units like the IDF Combat Engineering Corps’s Yahalom Unit, an elite commando unit whose soldiers specializes in finding, clearing, and destroying tunnels. The large force includes subordinate units like Sayfan, which trains to handle the threat of unconventional weapons, Samur, which specializes in entering, clearing, and destroying tunnels. The Yahalom is one of the largest units in the world that trains, mans, equips, experiments, and develops new ways to deal with underground warfare. The IDF’s canine unit, Oketz, has dogs trained for operating underground. And the IDF, police, and intelligence services all have special units—like Sayeret Matkal, the Yamam, and others—who share best practices for dealing with terrorists and combatants underground.
The Yahalom and other IDF units also have special equipment specifically developed for tunnels. Tunnel reconnaissance units, for example, use ground and aerial sensors, ground-penetrating radar, drilling equipment, and other systems to find tunnels. There are radios and navigation technologies that to work underground, night-vision goggles that use thermal and other technologies to see in complete darkness, and a suite of remote or wire-controlled flying or crawling robots that can look into and map tunnels without risking soldiers. The IDF also uses virtual reality training simulators that allow soldiers to train for underground warfare even when they aren’t at the physical training sites that include subterranean environments.
Israel has also developed special tactics for dealing with tunnels once they are found. It has a wide range of ground-penetrating munitions like the GBU-28, which can penetrate one hundred feet into the earth or through twenty feet of concrete. IDF ground forces also have multiple types of explosives to collapse or seal tunnels. They also have plenty of bulldozers they can use to seal tunnels—a tactic the US Marines employed when it sealed Japanese defenders in their caves and tunnels during the last part of the 1945 Battle of Iwo Jima. When multiple Hezbollah tunnels were discovered along Israel’s norther border during Operation Northern Shield in 2017, the IDF poured truckloads of wet cement into the tunnels to close them. Egypt is known for trying to neutralize Hamas cross-border smuggling tunnels along its border with Gaza by flooding them with seawater and sewage.
But the hard truth is that the depth and scale of Hamas tunnels in Gaza will surpass Israel’s specialized capabilities. It may come down to IDF infantry and engineers dealing with tunnels as they discover them.
It will also not be a simple matter of finding and destroying Hamas tunnels for several reasons. Gaza is not the mountainous and sparsely populated terrain of Afghanistan, for instance, where in 2017 the US military dropped America’s most powerful nonnuclear bomb—the 21,600-pound GBU-43/B Massive Ordnance Air Blast bomb—on an ISIS cave and tunnel complex. Moreover, Hamas will likely put weapons and explosives in tunnels that can trigger unintended explosions elsewhere or travel through to other parts of the tunnel network, causing damage where the IDF didn’t foresee. Finally, Hamas will likely put civilians and hostages in their tunnels as human shields. All of this means that Israel will have to take a deliberate approach to each of the tunnels they will discover.
There is no uniform solution to the problem that tunnels will present Israeli ground force, undoubtedly one of the biggest they will face in Gaza. Dealing with each tunnel will require a situation-dependent mix of capabilities. But above all, given the scale and complexity of the underground infrastructure in Gaza, one thing is certain: overcoming the challenges posed by tunnels will require a lot of time.
John Spencer is chair of urban warfare studies at the Modern War Institute, codirector of MWI’s Urban Warfare Project, and host of the Urban Warfare Project Podcast. He is also a founding member of the International Working Group on Subterranean Warfare. He served twenty-five years as an infantry soldier, which included two combat tours in Iraq. He is the author of the book Connected Soldiers: Life, Leadership, and Social Connection in Modern War and coauthor of Understanding Urban Warfare.
The views expressed are those of the author and do not reflect the official position of the United States Military Academy, Department of the Army, or Department of Defense.
Image credit: Israel Defense Forces
Flood the tunnels with the waters of the Med. You need several fire fighting tugs.
They should start digging large tunnels underneath all the hamas tunnels and put a lot of explosives in those tunnels underneath the Hamas tunnels and then Hamas should be swallowed up alive like korach and his die hard rebels
The 238 Hostages held by HAMAS are all in different parts of the tunnels. This includes 39 CHILDREN.
As a civil engineer, flood the tunnels sounds completely plausible and doable.
IDF cannot indiscriminately just DESTROY TUNNELS.. This would be EASY. The PROBLEM: The 238 Hostages held by HAMAS are ALL in different parts of the tunnels. This includes 39 CHILDREN from 7 month; all except 6 are under age 14.
I understand your emotion. But we need rational thought an not emotion in order to deal with Hamas. Several instances in the Bible God has to destroy evil people. You go to the top of Masada to be sworn in to the IDF. Why? When you explain why you will be less emotional and understanding of the reality. The hostages are gone. They are part of the death toll. Try to be rational and not emotional. To save lives in the future, far more lives than the hostages, we must eliminate Hamas, kill all of them. These savages, the Islamic State, they only recognize and understand power, force, and dogged determination.
It agree, same idea. Simple, fast, cheap and IMO the safest way to try and get hostages out to tunnels. Even add a thick foam, that covers and hides objects making it hard to find items to take with them.
Fighting down there, digging below them (LOL), in what time frame? Without them knowing? (LOL) Any other way results in shooting, explosions and death on both sides.
That is all part of Hamas plan,as the long as the hostages are known to be down there they won't be flooded.
I totally agree.
And what will you do for the hostages? There are stupidities that can’t be healed.
Valla dediğini yaptılar :)) Bence de mantıklı
Israel needs to develop armed sentry robots that can shut down underground traffic in the tunnel, then explode once engaged.
U can employ very toxic gasses pushed in at high pressure or wind in order to clear first kilometres. Gas them out
If HAMAS had combat gear what do you think they'd invest in before their attack. Gas masks or oxygen tanks? I'd still lean towards using water if still interested in attempting to recover hostages.
Why not drilling small yet in depth holes with suspected tunnel activity, the holes would be in 4 corners of suspected tunnels, dynamite and ropes will be inserted from edge to adge on all four corners, creating the crater as the holes in depth layer were drilled.
The hostages including the babies are gone. Time to unleash whatever it takes to destroy Hamas or this will just happen again.
Directional drilling can locate tunnels. Once located they can be quickly filled with odorless natural gas and blown. An, option to limit collateral damage on the surface would be carbon monoxide.
In the case of the Gaza Hospital complex if the grounds are occupied and the air intakes identified, CO, or even CS could be used to clear the tunnels.
Another option would be small ATV drones that trail communication cables. They could be fitted with sprayers to deploy, CS, Blister Agent etc. when they come in contact with combatants.
An elderly german man told me of his surrender to the British during the last few days of the war. Hidden in his tunnel, he recalled "they brought us out with flame throwers."
Thanks for sharing. I was looking for knowledgeable info on the challenges of the Hamas tunnels, and tools/techiques for underground warfare, this is super.
Q1: Do Hamas tunnels typically have designed "fighting positions" like castles of yore?
Q2: Have seen many Twittersphere-instant-experts and the like advocating for flooding the tunnels. Is that generally practical for a situation like this, where the goal is finding & killing Hamas, and denying them the use of the tunnels for movement and the supplies cached underground? My (also amateur) assumption is that if IDF finds a tunnel entrance, they'll want to explore all of its connections, and sterilize as much of the system as they can find. A gazillion gallons of water (arguably) impedes IDF as much as it impacts Hamas.
150 Decibels of sound pumped into tunnels can rupture eardrums, disorientate , and nauseate. Terrorists would not hear themselves or others, could not communicate with others. The tunnel diameter ensures little dissipation of the sound over long distances. It’s inexpensive. Easy to experiment with. I suggest heavy metal rock, or the israel national anthem.
I am afraid that Hamas has filled the tunnels
And underground hq beneath Al shifa hospital with fuel air gas thermobaric weapons. I am told it would not take much of these to blow the hospital and its neighborhood apart. Results could be equivalent to a small nuke Is this possible?
Q1: No first-hand knowledge… but all it would take is long straight-aways and strategically placed corners to easily defend. People entering would have to go straight with nowhere to hide/take cover, while defenders had the corners to hide behind.
Q2: Flooding works. Denies access, forces Hamas out in the open. The last thing they want to do is explore them… unless it is by robot (which would be a good way to map them). There is zero ability to maneuver in a tunnel and get out of the way of bullets. Some type of gas might work, but they have ventilation systems… so not sure how that would work on a large-scale. In Vietnam, they dropped colored smoke grenades down and sealed off the entrance… then looked where the smoke came out. But again, those were different tunnels and not constructed like Hamas' tunnels. All it would take are some doors to stop smoke or gas.
What they want is to seal off the tunnel entrances to prevent their future use and force them out in the open… (google "sponge bomb") if you keep doing that, you start limiting where Hamas can enter/exit. The last thing the IDF wants to do is get in a war of attrition with Hamas in the tunnels. That is exactly what Hamas wants… a fight where they have the advantage.
It's going to be chaos down there once the electricity runs out if it hasn't already.There is a slight chance that Hamas operatives may start to turn on the leadership or try to surrender with hostages as a bargaining chip.There is another remote possibility,the "Stockholm Syndrome"? I know some of the hostages a fluent Arabic speakers and are basically "peaceniks" who used to do charity work in Gaza.The longer they are down there together there is a chance they will start to form a bond?Name comes from a "Bank robbery in Stockholm while during a police siege the assailants and hostages basically began to empathise with each other".What I am saying is the longer this goes on some hostages may literally be able to talk their way out?That is a longshore but not impossible?Basically I think it's more of a wait out than a dramatic assault?
More than one way to skin a cat – Methane gas, unscented natural gas and for that matter any odorless flammable gas or something like fougasse would make life very entertaining for tunnel neutralization.
Sounds like Israel will lose this war, just like the war it lost in Lebanon.
As far as I’m concerned they didn’t lose that war.
I had reached the same conclusion : flood the tunnels. That way , even the deepest shafts and chambers will flood. I doubt they built flood proof doors in their tunnels.
Employ a large high bypass gas turbine engine thrust directed into the tunnel entrance add a fluorescent dye or otherwise, after 20 minutes the covers over any unknown entrances will leak very hot air or blow out, plus it be very unbearable for anyone inside , thermal cameras will easily pick up where the heat is escaping from, the beauty of this method is the volume of pressurised air is massive, given enough time this will work on almost any length of tunnel Employ a large high bypass gas turbine engine thrust directed into the tunnel entrance add a fluorescent dye or otherwise, after 20 minutes the covers over any unknown entrances will leak very hot air or blow out, plus it be very unbearable for anyone inside , thermal cameras will easily pick up where the heat is escaping from, the beauty of this method is the volume of pressurised air is massive, given enough time this will work on almost any length of tunnel
I read this 5 weeks after Israel started its ground campaign. Based on Spencer's assessment of the tunnels' advantages, you would think that Israel had many hundreds of soldiers dead and hordes of armor destroyed by now, countless smoking wrecks created by Hamas' crack anti-tank squads as they popped up from their ubiquitous tunnels. Reuters would gleefully post photos of these on social media, so perhaps Spencer will go find them for the reporters.
I just can't figure it out, how HAMAS are managing the supply of their weapons in fighting IDF whenever I see the GAZA map??
Best solution- occupiers leave and let the Palestinians have their stolen home back.