The Decibel - Gaza’s underground tunnels

Episode Date: November 23, 2023

Israel and Hamas are negotiating a four-day ceasefire which could see the release of up to 50 prisoners being held in Gaza as well as Palestinians currently imprisoned in Israel. Israel said that for every additional 10 hostages freed by Hamas, the truce would be extended by a day.It is widely believed that hostages in Gaza are being held in a system of tunnels underneath the territory. This subterranean network is believed to have existed under Gaza. But how big and connected the tunnels are remains still unclear.Drew Craig is a consultant geologist and a member of the International Working Group on subterranean warfare, based in England. He’s on the show to tell us what we know about the tunnels and how it’s made the strategy of this war even more complicated.Questions? Comments? Ideas? Email us at [e-mail]

A four-day ceasefire is currently being negotiated between Israel and Hamas. It's a first in the war, and as part of the deal, up to 50 hostages being held in Gaza will be released, as well as Palestinians imprisoned in Israel. Both sides will let women and children go first. It's widely believed that hostages in Gaza are being held in underground tunnels. By now, you've probably heard about the Gaza tunnel system. That's because it has a crucial role in how the war is being fought in Gaza.

But there are still things that remain unclear about the network. Drew Craig is a consultant geologist and a member of the International Working Group on Subterranean Warfare, based out of southeast England. He's visited tunnel systems around the world that have been used in warfare. Today, Drew is on the show to tell us what we know about Gaza's tunnels and how they're being used in this war. I'm Maina Karaman-Wilms, and this is The Decibel from The Globe and Mail. Drew, thank you so much for being here. Oh, you're very welcome. Thanks for letting me join you.

So let's talk about these tunnels. Hamas claims that this tunnel system stretches over 500 kilometers underground. The IDF, the Israel Defense Forces, they say the system is used to store weapons and includes military headquarters. But these tunnels do remain a bit of a mystery, right? So I guess how do we know that they actually exist? A mystery to the extent that we don't really understand where they are. But Hamas themselves have been very open about bringing reporters down into these tunnel systems and effectively showing them around. A quick look on any one of these video platforms will show innumerable interviews and guided tours showing a range of underground

features, those tunnels, a standard communication tunnel, as we'd call it, to move from A to B. And then those functional spaces where it might have been for command and control or weapons engineering or storage and the like are also shown that are significant in size. So there's a lot of information out there already to demonstrate the fact that these tunnels are there. What we just don't understand is the true extent of how far they sit throughout the Gaza area, or indeed their orientation and sort of the overall scale and size of what the network looks like. What you may have is lots of smaller zones of networks. How interconnected those sort of little zones are, we don't yet know. Okay. And a recent flashpoint in this war, of course, has been the Israel Defense Forces targeting of al-Shifa Hospital in Gaza. And so there's a lot being said about

this hospital. The IDF says it sits on top of an underground Hamas command center. Hamas denies this. A former Israeli PM told CNN that Israel actually helped build some of the underground spaces beneath the hospital. When you say it was built by Israeli engineers, did you misspeak? No, no, somebody, you know, decades ago we were running the place. So we held them, it was decades, many decades ago, probably five, four decades ago, that we helped them to build these bunkers in order to enable more... And of course, over the weekend, the IDF released a video of what appeared to be a tunnel shaft with a circular staircase going down. ...then turns into a corridor, walks down that corridor about 200 meters.

We see at the end of that corridor a blockaded door that is fireproof, that has a shooting hole through it. This is a terrorist tunnel. But have we learned anything conclusive about what is actually underneath Al-Shifa Hospital? This is certainly evidence. They've evolved to the point now, or the updates have evolved to the point now that we know the IDF have gone through the protective door, which was at the end of the corridor that they had gotten to on the first video. So this is, sorry, down, there's a staircase down, there was a tunnel and there's a door at the

end of that. So there was a vertical shaft, partially collapsed due to the, I guess, battle damage. It appears that there was a metal circular staircase descending down through that shaft that then led on to a horizontal tunnel of some 50 or so meters. So the IDF managed to get an asset down into that using a video camera to see what was going on. That took them as far as that blast door. We've not seen anything more. I had a quick look before I joined you to see if there's any updates to that. And there's nothing as yet. But one would expect to see a sort of drip feed of further information as they investigate further into what this system looks like.

All right. So let's talk a little bit more about what we do know then here. Can you paint us a bit of a picture, Drew, about what we have learned about these tunnels? A lot of the footage you will commonly see will be of a narrow tunnel about the width of a person, about the height of a person, typically with concrete panels along the sides and an arched concrete cover over the top, over the ceiling. And these are concrete preforms that are effectively inserted into the tunnel once they've been dug. Now, these tunnels are actually constructed with, shall we say, relative ease. The underlying geology that they've gone through is quite soft.

It's effectively a marine sediment, sort of beach sediments, poorly consolidated. And by that, I mean, you can sort of dig away at it quite easily. You don't need to drill and blast, which is what you'd see in much sort of harder rock. So the tunneling is relatively easy in that regard. And when you're saying digging, I mean mean just like people with shovels down there how's that done pretty much yeah pretty much um really really soft rock so definitely you could use a shovel or small hand tools to sort of uh you know eat away at the at the wall the the face as you sort of progress the tunnel in. But effectively, having then created the space, you then need to protect yourself like in any tunnel engineering where you would then tunnel in and then you would shore up behind you.

And that's where those concrete preforms come into play. They're then installed to secure the tunnel behind. How deep do these tunnels go? You know, you're talking potentially tens of meters. The geology will dictate that to some degree. The other factor that comes into play is the level of the water table. So the closer you are to the coast or the closer you are to some of the water features, the drainage features that run through the terrain, the higher the water table will sit

within the rocks. And what you don't want to be doing is digging a tunnel and then having it sort of flood. So that will dictate to a certain extent how deep those tunnels are. But certainly the indications are that they're tens of meters or getting down towards tens of meters deep. But some of the tunnels equally will be quite shallow. And we've seen tactical tunnels being used that have enabled troops to effectively pop up, effect a quick attack of some form or other, and then to retreat back into the tunnel to get away. So let's look at those as being tactical tunnels and compare those with the deeper communication tunnels that would interconnect to the effectively the mission spaces. What about the entrances to the tunnels,

Drew? Do we know what they usually look like, where they usually are? Wide and varied. So the tactical tunnels that I mentioned earlier on are potentially just an open hole somewhere, potentially more in the more rural areas just covered over with scrub but certainly the indications are that we have tunnel entrances that are within buildings there was one video that came out about a week or so back that showed a let's call it an abandoned car in a car car park and the tunnel entrance actually came up inside the car. So concealment of these access points is probably, you might say, a bit of an art form. But they are fixed points.

So once they're identified, they can then be closed off or exploited. And what about things like communication power sources down there? What do we know about that? So most of those tunnels will have power. They will have communication cables running through them. If you're underground and you're in this confined space, you need to be turning the air over. So there will be some form of air conditioning involved as well. So to that extent, they're relatively sophisticated in that they have been fitted out with what we define as what we call the umbilicals. So Hamas is thought to have begun dugging these tunnels potentially in the mid-90s, maybe even before that. We don't exactly know, it seems. But why were they built in the first place?

Well, the original tunnels in Gaza, and you're right, goes back probably a couple of decades, if not longer, were originally along the Egyptian border, and they were predominantly for smuggling. And their scale and, again, their depth varied, but to the point that in some cases you're potentially able to drive a car through a tunnel. So really significant. But that capability obviously evolved. Clearly, we've seen the sort of political changes in Gaza over the years as well. And now with Hamas, those tunnels are being dug exclusively for military means. Drew, I know that you've actually been in a tunnel, not in Gaza, but at the border between Lebanon and Israel, where there's also tunnels.

Can you tell us what was it like being down there? Well, I think the one thing I was most struck about was the scale of what had been done. And I was there in December 2019. Unlike in Gaza, you have effectively hard rock geology up in the north of Israel along the border with Lebanon. It's dolomite and limestone. But the scale of some of those tunnels was rather incredible. But running water, again, communication, cables, telephones, power and the like in order to be able to put those tunnels in. So really quite dramatic and impressive.

It's tight. It's claustrophobic. I've been very lucky to visit a number of tunnels related to warfare around the world, ranging from the tunnels of Cu Chi in Vietnam through to some of the tunnels within the Dolomites which were used during World War I and it's incredibly claustrophobic which I guess leads to the conclusion that an underground warfare is not suited to everybody. I mean both psychological conditioning and physical conditioning plus the right equipment in order to be able to operate within that environment. So very, very challenging in that regard. But yeah, really fascinating to see it. The level of engineering was what I was particularly struck by. We'll be back in a moment. So as you mentioned, Drew, this is not the only example of tunnel warfare. There's a long history of this, actually.

Can you just remind us of some of the other situations in the past where tunnels were used in urban warfare? Sure, yeah. So underground warfare has been around for as long as warfare itself has existed. It's nothing new, but much like we normally do, we have to continually relearn the lessons hard won by others. I guess if we go back to World War I, not necessarily so much in the urban environment, the use of tunnels to emplace large explosive charges beneath the enemy lines and then detonate them as a prelude to a ground assault. We've seen that technique used since more recently in Syria, for example,

with the rebel forces in Syria using that technique to attack the Syrian government forces. The other obvious one in an urban context would be more recently in Mosul and Iraq, where there was extensive use of tactical tunnels made. In some cases, these were open trenches that were subsequently covered over. In other cases, they were actually excavated underground, but they allowed the Daesh insurgents to move quickly from site to site without being seen. And that's one of the key reasons why people have gone underground. It's don't be seen with the secondary aspect of, you know, don't be hit. So the tunnels offer protection from site and protection from the various weapon systems that are employed these days.

Yeah, you said Daesh was using this title. So that's ISIS who is using those tunnels there. Correct, yes. Every urban battle space has really had some element of sub-T to it. Because if you think about any city, there are going to be sewers, there are going to be areas where there is power, there's something else, infrastructure is being run through a subterranean space, subway systems, railway tunnels, road tunnels, all manner of things. And therefore, whatever you see above surface, as I've said, you've got the other super surface

element, you're just as likely to see something multiple levels below ground as above ground. I guess I'm curious, though, Drew, because we've had major advances in technology, right? We can find things underwater. We can detect things in space even now. So I guess why is it that tunnels, especially these ones under Gaza, why are they so hard for us to detect? I think there's lots of technology out there. So, you know, I work in the mining sector and we've got a myriad of systems that we can use from aircraft to satellite to systems that are on the ground.

Now, clearly, anything that's in the air or in orbit as a satellite has the standoff to be able to look at something. But sometimes you physically need to be above something, boots on the ground in order to use a particular geophysics system. So if you take that and put that into a military context, that requires securing a piece of ground and having the freedom of maneuver to go about utilizing a piece of geophysical equipment in order to try and identify a target. That's just a target. You don't necessarily know what that means because we we can't quite x-ray down through the the earth yet uh that may come in in years to come but we don't have that technology right now so we have to analyze the data that we can collect to generate targets and then very much as we've we we saw with the israelis uh in uh 2018 on the lebanese border having identified targets through through a variety of means,

including traditional intelligence gathering as well, to then try and target those tunnels to intercept them. And what they did there was initially drill down to see whether they could intercept the tunnels and having effectively put a drill hole into a tunnel, put CCTV cameras and other systems down to then work out what was going on and then work out how best to deal with a particular tunnel. In one case, the tunnels were destroyed through explosive means. The Israeli Defence Force gave a certain amount of verbal warning to what was going on. Loud hailers, loudspeakers very overtly said, we're going to blow this tunnel up and then did so.

And then the other means through which they denied access to the tunnels were effectively pumping them full of concrete to block them in that regard. Anecdotally, if you go back, the Egyptians actually denied access through the tunnels between Egypt and Gaza a number of years ago by actually flooding them with sewage. But clearly the presence or the potential presence of hostages is probably playing heavily on most people's minds right now. And therefore, anything that's being done is having to be thought through very, very carefully. I'm glad you brought up the hostages because I think we should talk a little bit about this as well because Israel has stated, of course, that its goal is to destroy Hamas

and part of that mission has included targeting those tunnels. But we do believe that a lot of these hostages, if not all, are being held in these tunnels, right? So is it possible to destroy these tunnels without harming the hostages? So I used the term denial earlier on. Most people, if you say, I'm going to deny that tunnel, will think, oh, you're going to fill it in or you're going to destroy it through explosive means. That might not necessarily be the case. You can deny at least partial use of a tunnel or the broader system just by blocking off an entrance. And there's been a bit in the media about the Israeli Defense Force sponge bombs, which effectively is a two-part chemical that mixes and generates a

foam that then hardens. So there are various other ways that you can deny access or deny utilization of a system without necessarily causing damage to the people who may be in that system. And there is, of course, a lot of anticipation that fighting in this Israel-Hamas war will eventually go underground into these tunnels. What would it be like to fight down there? Well, again, incredibly challenging. And I think the approach so far from the IDF appears to be don't engage in the tunnels. Hamas want to draw people in, and therefore the IDF appears to be very reticent to do so. They're leveraging drones, be it ground drones or aerial drones. They appear to be using military working dogs and anything but putting a human being down into a tunnel.

Clearly, we're seeing the tip of the iceberg in terms of what's going on there. I'm sure stories in the future will come out. But certainly in the past, it has been important to go into these systems and clear them. It just remains to be seen as to how much of that is actually going on in Gaza right now. A four-day ceasefire has been agreed to now, and that is supposed to mean dozens of hostages may be released soon, at least 50. And when that happens, I guess, will we learn more about the tunnels, Drew, given that we think those hostages may be released soon, at least 50. And when that happens, I guess, will we learn more about the tunnels, Drew, given that we think those hostages would have been held down there?

Well, those hostages who have already been released have alluded to the fact that they were taken down into tunnels. Now, how much the hostages who will hopefully be released soon may be able to, how much information they may be able to pass on very much depends on how much they were moved around, how regularly they were moved around, what they were able to see and hear and feel and touch, I think is really too early to say. And also, I think we should bear in mind that it appears to be that a lot of the hostages who are going to be released are very young children, And therefore, how much information they may be able to pass on, again, could be a challenge. I guess just to end here, Drew, you know, all this being said, will we ever actually have a full picture of these tunnels, the extent of them?

Will we ever really know this? No, I don't think we will. In the end, and I'm not sure when that end might be and what that end looks like, but I think we'll have a good idea of where those tunnels are. And certainly there's headlines around the hundreds of access points that are being identified. So I think we'll get an idea of the distribution of the tunnels from those access points. As to what the web of tunnels underneath the ground potentially looks like, I don't know. It very much depends on how much of that is actually destroyed, how much of that's been surveyed prior to destruction.

And I guess that information will sit with the IDF and maybe we'll learn in due course, but who knows. Drew, thank you so much for taking the time to speak with me today. No worries. Thanks for having me. That's it for today. I'm Mainika Raman-Wells. Our producers are Madeline White, Cheryl Sutherland, and Rachel Levy-McLaughlin. David Crosby edits the show. Adrian Chung is our senior producer, and Angela Pachenza is our executive editor.

Thanks so much for listening, and I'll talk to you tomorrow.