Tracing Gaza’s Terrorist Tunnels with #OSINT

In the wake of a devastating terrorist attacks committed by Hamas against Israel, with open-source techniques exploring and investigating the terrorist tunnel system.

9 min readOct 23, 2023
AI Art

How could the terror organization Hamas and the Al-Quds Brigade, the military wing of the Palestinian Islamic Jihad (PIJ) build the over 7,000 rockets sent towards Israel alone in the past two weeks since the horrendous attack?

Sure, terrorist organizations all over the world are able to plan and assemble weapons. Some also built tunnels. But this case is special. Smuggling of military parts into “the largest open air prison”, as some call it, sounds like as ludicrous, laborious, costly and difficult to manage as one can only imagine.

The tunnel system aids terrorists to assemble and build weapons, embed explosives in rockets, and fire them towards Israel. On October 7, tunnels helped to execute one of the most devastating attacks. To this very moment of writing, these tunnels likely remain a prison to those hundreds of hostages taken by Hamas.

How could this happen? And perhaps more pressingly: What will the Israeli defense forces need to expect when they enter the tunnels?

Hamas Tunnels: A long-term study

One non-consoling part of the answer is, Israel knew for over a decade the capabilities of this tunnel network, and that Hamas were keep building them. Some — actually a lot of them — got wiped out. But like the head of a Hydra, they just kept on growing new parts to the system.

To find out what’s going on and what role the tunnels played in the recent attack on Israel, I spoke with one of the foremost experts on the Hamas tunnel system, Eado Hecht, a defense analyst at The Begin–Sadat Center for Strategic Studies.

2014: Hechts observation — A typical entrance to a tunnel in the basement of a house in Gaza found by Israeli
troops. Note the white sacks that were originally used to distribute food or other
commodities to Palestinian refugees by UNRWA (red circle).
They were being used as camouflage to evade detection by Israeli intelligence
services — bringing building materials to the tunnel and extricating the soil dug up
from within the tunnel and in some cases covering tunnel entrances — Source

Hecht gave testimony to the UN Commission nearly ten years ago and explained the Tunnel in such forensic detail, that he seemed the right person to question about purpose and structure. He compared the tunnels back then with the those built by the Viet Cong — who, over a couple of decades, dug extensive tunnel systems as safe havens from South Vietnamese and American troops. Though there were other examples to choose from, Hecht chose it because of their defensive nature and because it was a prominent example.

Today, he says the Vietnamese tunnels were built a bit differently because of the soil differences. However, the tactical idea — notably the survivability for the forces against detection and fire, ability to travel underground over long distances, ability to pop up and surprise enemy troops or shoot from hidden slits, etc. — are comparable. “So if someone wants to understand the general concept, I refer them to the Vietnamese. A major difference being that the Viet Cong did not have to cross a border”.

Hecht maintained a sharp eye and gathered detailed intelligence on those tunnels back then. On photo evidence of white sacks near the Tunnel entrances, Hecht highlighted logos of the Palestinian refugees program UNRWA (above).

With maps and illustrations, he communicated the depth and conditions of the early smuggling and attack tunnel infrastructure by Hamas, a decade ago. What has changed since back in 2015?

Some stress, that after 2014 the tunnels became longer, wider and deeper than before. It seems Hamas has also improved on the efficiency of building them. New tunnels can be dug fairly quickly, with some estimates that a meter per day can be dug with tools as simple as a DeWalt hand drill, one expert told NBC News.

Hecht also insists, the terrorists built them using manual labor —they are hiring people to work. “They would be taken to a closed van, so laborers wouldn’t see where they were. They would work very long shifts. Then be taken out the same way and driven to some place else”, he says.

They have building engineers who designed what they needed to know. The concrete is purchased as building materials for houses in Gaza but diverted — that is why Israel put a freeze on import of concrete for a time, but international pressure would have compelled Israel to let them continue to import.

The so-called siege of Gaza is not a siege — they can generally import anything but military equipment and some important dual-use items. These they smuggle in overtime through Egypt or through Israel disguised as ordinary civilian items — the IDF once caught a shipment of canned food which actually was electronic parts hidden in the cans instead of the food, he adds. Israel and Egypt monitor the entrances — the Erez crossing, which was attacked and captured on the first day, was one of the major entry and exit points for imports and exports and passage of people. It allowed the 20,000 Gazans who came into Israel every day to work.

I showed Hecht a special video, the self-promoting footage of the Al-Quds Brigade (AQB) terrorist group in Gaza. The video is one of the few most recent pieces of evidence on the rocket tunnel infrastructure, how the AQB, PIJ’s military wing, maintains it.

The video was posted on October 9., two days after the terrorists crossed the border. It’s not sure whether the footage was, in fact, filmed and produced after the attack, or merely “prepared”, so filmed before it. If it was, then it would tie the majority Iran funded PIJ directly to the attack by the Hamas.

Telegram link of Video: Text of video: “Intense missile barrages towards “Beersheba” and the cover settlements as part of the “Al-Aqsa Flood” battle”

What is Hecht’s view of the video? After years of analyzing images and footage of Hamas Tunnels, he says he has not seen anything new here. “Of course, they are careful not reveal anything that might help us locate and destroy the tunnels”. Open-source observations allow gathering some additonal insight.

Unguided S-40, 40km rockets identified, these are domestically made, and produced underground in secured missile production work stations
The video shows how the missile types being shoved into a hole in the ceiling of the tunnel structure
Light, power, and religious ideology: reading “But god is there”

Hecht explains the defensive tunnels are a warren under Gaza. They include storerooms, command posts, medical stations. They enable travel between different areas without coming above ground, and they have multiple entrances and exits, so they can come out where and when they want, fight, then run back down to disappear, either shutting and camouflaging the entrance again or exploding it to prevent IDF troops following them.

The video shows they are also, at least in this part, fitted with electricity and lights, and may serve in part as religious sites, as the paintings and graffiti on the walls let assume.

Schematic Illustration of a Cross-border Tunnel Discovered by the IDF in 2013 (nearly a year before the summer 2014 war). The tunnel entrance was inside the Gazan village of Abasan al-Zrir.
It was aimed to reach the Israeli village of Ein HaShlosha, but the diggers could have
changed direction further on to the village of Nirim.

Hecht explains three major things have changed since his testimony. Since Israel built the underground wall, the smart wall on the Israel-Gaza Strip border, Hamas hasn’t been able to use the tunnels to infiltrate into Israel.

Illustration of the underground-enforced wall against Hamas tunnels, WAPO piece, puplished Oct 10

At the attack on October 7, it is the reason Hamas fighters had to leave the tunnels on their side of the border fence, Hecht says.

The new border wall is big. It is not impossible to bypass the wall, but it makes the digging much-much more dangerous and expensive because they will have to dig through the natural aquifer. They found a solution that worked, he says. What that “solution” might be, he doesn't say.

However, the fact that Hamas dug “many more kilometers of defensive tunnels inside Gaza”, is testament enough that it clearly works.

The third thing that changed is that Israel could amass and acquired much better intelligence than it had in 2014 on their locations. So much so, “that we have already destroyed quite a lengthy stretch of tunnels in Guardian of the Walls and again during the past few days”. However, Hecht is aware of the limitations.

“It is NOT perfect intelligence”, he stresses. He do not know what percentage of tunnels we know of and how much will be left after the bombing. While we don't know either — Open-source intelligence would take months or even years to gather, and might never be as complete as those of Israel — traces of how and where smuggling tunnels were built are published by the IDF in part.

Instead, it warrants looking at examples. Hamas embedded their tunnels entrances deep in the humanitarian and social lives of people. Entrances, so IDF intel, found them at and near clinics, schools, factories, Universities, along UN sites, and welfare centers.

Weapons manufacturing sites embedded into the tunnels, are just part of the system, and Hamas uses both these and external positions too, he adds. “If they are left only with those in the tunnels, it will reduce their rate of fire because firing many at once requires creating a field of multiple-barreled launchers”.

A number of geolocateable sites published 2022, where Hamas and the Al-Quds Brigades built under Tunnels and weapon manufacturing sites in the middle of civilian life of Gaza

I asked Hecht about the strategic importance of the Tunnels for Hamas, and whether Hamas will be able to maintain or even expand its Tunnel Metro?

The tunnels’ strategic importance of the offensive tunnels was demonstrated on the first day of the Terror Offensive, he explains. They ensured the terrorists could arrive at the fence undetected.

“We now have to detect all of them and destroy them. The ones they used will be easier because they now have openings, even if very small ones, the ones they haven’t used will be harder and will be a threat to the rear of our troops if and when we go into Gaza on the ground”. Hecht’s answer sheds light on open-source techniques to find the exit holes of the buildings. To locate entrances under buildings, in basements etc, it will require various intelligence sources. From tracking geolocations of phone data, over satellite intel to human sources. All this might be extremely tough in the current conflict scenario.

One way to spot new tunnels — check on old example. Here, the IDF bombed out a 2016 Hamas tunnel system leading into the water. The idea behind it was to allow frogmen to capture packages, deposited by ally Iran in the water, allegedly containing weaponparts, before being carried it back to base covertly.
2023 areal bombing by IDF, claiming to hit “tunnel exits” — videos with allegedly entrances showing up on tape to tunnels in Gaza can be traced and tracked with Google Earth Pro

Tunnels can (but don't necessarily have to) also connect to rocket launch sites. With high-res images, argues the IDF on social media that Hamas launch sites are positioned near UN sites:

Link: Twitter X: “This UN building sits directly across from a Hamas rocket launch site used to terrorize Israeli civilians. Hamas directly endangers Gazans, Israelis and the international community. Click the thread to see where Hamas put their other rocket launchers” — Note: whether the claims and the places indicated are what IDF states, is at this stage not independently verifiable

The Tunnels protect Hamas from not only Israeli aerial observations but also from aerial bombing, tells me John W. Spencer, a now retired US Army officer and researcher of urban warfare.

WSJ visual piece on 2014 Tunnels. These large maps just doesn't exist publicly any longer.

Without the tunnels, Hamas is defenceless. Hecht stresses that the defensive tunnels are the basis for their survival — “those we know about are being destroyed by the air force, the ground penetrating bombs. Those we don’t know the exact trace of, will serve as shelters and fighting positions that will reduce our ability to kill them while increasing their ability to ‘pop out’ and attack IDF units by surprise, causing us more casualties, he says.

But Hecht also sees one major hurdle. If the war drags on, Hamas will be able to gradually dig more. But only if they somehow can keep accessing building material. “Without concrete, they will be more prone to collapse”.

Probably more or less, what they have left after the bombings is what they will have for the ground fighting now, he says. If the Hamas terrorists survive this war, it will be only a matter of time for them to start digging again, and build new tunnels and repair partially damaged old ones.

Read the full story on Süddeutsche Zeitung: “Hamas’ secret network”

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Investigative journalist with a technical edge, interested in open source investigations, satellite imgs, R, python, AI, data journalism and injustice