16 years of rule in the Gaza Strip have allowed Hamas to build defenses through a labyrinth of tunnels and underground caverns, the like of which no terrorist organization has ever built before. Hamas claims that the network comprises 1,300 tunnels, spanning over 500 kilometers. For comparison, London's underground railway (the tube) extends over 400 kilometers. However, Hamas's claims should be viewed skeptically. In Operation Guardian of the Walls in May 2021, for example, the IDF said it had hit 100 kilometers of tunnels overall.
Regardless, this is the most expensive and grandiose construction project that has ever been carried out in the Gaza Strip. According to estimates, the cost of excavating each meter ranges between $200 and $300, so total excavation cost about $150 million. The Hamas tunnel network, according to various reports, is as complex as a road network with main tunnels for fast movement, bypass tunnels, sea tunnels for the exit and entry of terrorist boats, and tunnels that even allow traveling on motorcycles.
The tunnels include countless explosive charges, trap doors and other booby-traps that could endanger the lives of anyone who enters them. The military pressure currently being exerted by the IDF and the Shin Bet in the Gaza Strip is aimed at damaging the infrastructure and leadership of Hamas and obtaining information about the fate of the hostages, but the tunnels, often called the Gaza Metro, pose a massive challenge. From the shafts, Hamas terrorists fire rockets all over the country, and most of the activists and are hiding inside them and apparently the 240 hostages are being kept captive there.
Although the terrorist organizations have prepared for a long stay underground, it won't be easy for them. "It is difficult for terrorists to live for such a long time without sun, light and clean air," says Dr. Harel Horev, a historian and expert on Palestinians at Tel Aviv University's Moshe Dayan Center. "The tunnels are very humid and require constant ventilation, which leaves them more vulnerable."
He adds that the tunnels represent part of Hamas's security doctrine as well as of the pro-Iranian axis of resistance's doctrine called "forward defense." "It is a concept in which a terrorist organization wins wherever it exists and in which the role of the citizens is to protect the terrorists. Therefore, you will not find that Hamas provides shelter for the residents of Gaza in the tunnels, apart from their family members, because their role is to be outside and absorb the IDF's bombings."
The difference between the various tunnels inside Gaza
Prof. Joel Roskin, a geomorphologist and geologist in Bar-Ilan University's Department of Geography and Environmental Studies distinguishes between three types of tunnels. Firstly shallow tunnels at a depth of 10 meters, where activities that are accessible to the ground take place and can be detected relatively easily using ground-penetrating radar. These tunnels are connected to rocket launch shafts. Secondly, tunnels at a depth of 20-30 meters where Hamas terrorists store most ammunition and logistical equipment, and where most soldiers stay. Thirdly tunnels at a depth of up to 75 meters, where the headquarters and nerve centers of Hamas are located.
In Prof. Roskin's estimation, the Hamas leadership that remains in Gaza and the abducted Israelis are located at this lowest depth. "The groundwater is right at this depth, and it is possible that Hamas pumps it to supply itself with water during a siege," he explains. "There is electricity, food and equipment in the tunnels, and you can hardly feel the bombings from above. However, the generators that supply electricity to the tunnel system need air, so it is estimated that they are close to the surface, and this is the Achilles heel of the tunnels."
The tools to fight against the underground threat
Since the war broke out in Gaza, the Israel Air Force has been hitting as many targets as possible. Before the infantry and tanks entered the fray deep in Gaza and in particular into the terror tunnels. Among other things, the IDF is achieving this through bunker-buster bombs.
"Bloomberg" reports that in the past Israel has procured from Boeing GBU-39/B small diameter bombs for $735 million. These bombs each weigh 110 kilograms and can be fired from a distance of 64 kilometers and penetrate concrete bunkers 100 centimeters thick.
In addition to these US armaments, the Israel Air Force also possesses Elbit Systems MPR-500 multi-purpose rigid penetration and surface attack bomb. Weighting 250 kilograms, the bomb is designed to penetrate concrete walls and explode afterwards. Considered more reliable than comparable bombs, it has been proven in previous operations in targeted countermeasures that allow surgical damage to apartments where terrorists are hiding, without damaging the entire building. The bomb can penetrate, according to estimates, to a depth of 30 meters and even deeper.
In addition, the UK "Daily Telegraph" reported last week that the IDF has a special device known as a "sponge bomb". This is a chemical device that swells into a large lump of sponge and hardens to seal a tunnel. The purpose of the bomb is to block tunnels and prevent terrorists from escaping, or to encourage them to exit through controlled openings However, according to the report in the UK, the sealing ability of the bomb is limited, and therefore cannot deal with all types of tunnels.
This week, the IDF also unveiled a special robot for tunnel warfare, which is in the service of the Samur unit of the Engineering Corps., the engineering unit for special missions. The robot resembles the ones that NASA sends for missions on Mars: it is a kind of rover that includes five cameras and one pair of pliers. The robot transmits images from the depths of the tunnels to soldiers and military headquarters, and is also capable of detecting and initiating explosive charges.
The robot enters the tunnels before the engineering soldiers, clears the way ahead and gathers information. However, according to the estimates, the robot's ability to operate at a great distance from the control position is limited, and this is due to the difficulty in transmitting electromagnetic signals when underground. In addition to robots, the "Daily Telegraph" published information about drones equipped with night vision that penetrate underground tunnels.
Along with the IDF's technological advantage, the Hamas tunnels are built to deal with the IDF's toolbox, according to various reports. Some of the tunnels are built to thwart smart robots by building stairs and special slopes. Also, some of the tunnels are built in a "zig-zag" pattern, which disrupts communications.
One of the questions that arise recently is why the army does not simply flood the tunnels, thus drowning the Hamas terrorists. In 2018, the IDF tried to do this on the northern border, when it flooded the Hezbollah tunnels with water, then with bentonite (a water-absorbing mineral), and finally with another material including cement and thus filled the tunnel from Lebanon.
However, Hamas may have built a drainage system that includes canals and ponds. "Flooding with sewage has proven itself in the past on the Egyptian side (in 2015, Egyptian President Abdel Fatah El-Sisi ordered the flooding of a tunnel from the Gaza Strip after an incident at the border).
"It is a liquid that does not permeate easily, it is viscous and also has an unpleasant gas effect," explains Roskin.
What is the difference between Hamas and Hezbollah tunnels?
According to Roskin, the soil in Gaza is soft and makes it easy to dig tunnels, which made it possible to build an entire underground city in Gaza. "The ground in the center of the strip is made up of loess soil, a mixture of sand, clay and calcareous biochemical sediment, which makes the digging task relatively easy, although it is much more difficult the deeper you go," he says. "For comparison, the chalky soil in southern Lebanon is much harder."
In addition, unlike the Gaza Strip, a relatively small area of 540 square kilometers, Hezbollah has a larger geographical space to spread out and dig in, including buildings and thick vegetation. Therefore, the Lebanese terrorist group is not required to move its entire logistical and human organization underground.
Published by Globes, Israel business news - en.globes.co.il - on November 1, 2023.
© Copyright of Globes Publisher Itonut (1983) Ltd., 2023.