The first smuggling tunnels in the area were built by Bedouin clans on both sides of the Egypt-Gaza border after 1981, when Israel and Egypt demarcated the border. The first known tunnel attack from the Gaza Strip took place in 1989. But it was in 2001 that Hamas, the militant group that would later take over the area after Israel withdrew in 2005, began building a remarkable underground network. The original purpose was to smuggle materials and weapons out of Egypt. But the tunnels had many other uses.
Commanders could hide in them and use them to communicate without having to rely on Gaza’s telephone network, which is tapped by Israel. They provided shelters for weapons and ammunition. Hamas could use them for ambushes during Israeli ground wars in Gaza. And they allowed cross-border raids into Israel for attacks and kidnappings — such as the 2006 kidnapping of Corporal Gilad Shalit, a raid that later helped Hamas secure the release of more than 1,000 Palestinian prisoners. Hezbollah, the Lebanese militant group, built similar tunnels on the Israel-Lebanon border, although most were destroyed in 2018-2019.
The military rationale for such tunnels was ultimately to erode Israel’s style of war. “In 2008,” said a Hamas commander, reflecting on a short but intense war for Gaza that winter, “the airstrikes and aerial surveillance [by Israel] took us by surprise…so we made strategic plans to move the fight from the surface to the subsurface.” In 2014, the group’s tunneling operation employed 900 full-time workers, with each tunnel taking three months to complete and costing an average of $100,000 to build, according to a study by the RAND Corporation, a think tank. Hamas has raised capital for the tunnels and presented them as commercial investment programs, complete with contracts drawn up by lawyers, through mosques in Gaza. Iran and North Korea are said to have helped with construction, supplying money and engineers.
In 2014, the IDF launched Operation Protective Edge, an air and ground war targeting the tunnels. It destroyed about 32, with a total length of 100 km, of which 14 entered Israeli territory. That was a small part of the entire network, which was thought to include 1,300 tunnels, which Hamas said stretched a total of 500 kilometers – more than ten times the length of Gaza itself. An investigative commission concluded after the war that the IDF was unprepared for the danger posed by the tunnels, despite warning the country’s political leaders that they posed one of the five most serious threats to the state. Israel’s Defense Minister boasted at the time that it would take only a few days for the IDF to destroy the tunnels it was targeting; it took weeks.
Locating tunnels proved extremely difficult. “We were familiar with the tunnels mainly in theory,” said General Nadav Padan, who commanded a division in 2014. “We had no operational experience.” (General Padan, now retired to New York, returned to Israel on October 8 to rejoin the IDF.) The IDF used “geophones,” as well as ground-penetrating radars, which convert ground vibrations into voltage, and detection of echoes from controlled explosions, a technique honed in the oil industry. But many tunnels were discovered thanks to human intelligence – sources in Gaza – or infantry patrols who happened to find the entrances. Israeli intelligence units also looked for cases in which Palestinian phone signals would suddenly disappear.
Even if a tunnel was found, destroying it was another matter. The Israeli Air Force attempted to drop precision bombs along the tunnel’s route, a practice called “kinetic drilling,” but some failed to detonate at the correct depth. The IDF also used ‘Emulsa’, a gel-like explosive, but each tunnel required nine bombs. to an average of 11 tons of the stuff, RAND notes, forcing ground troops to secure entrances for long periods. Units often had to improvise; some borrowed carts and agricultural implements from Israeli border villages to transport explosives into Gaza.
In the past, IDF personnel tried to avoid fighting in tunnels, many of which were booby-trapped. The army high command forbade troops from entering unless one end was blown up or secured; This order was ignored only once, in 2014, when the body of an Israeli officer was snatched from a tunnel in Rafah, Gaza’s southern border crossing with Egypt. The ban made sense. In many ways, underground warfare embodies the most difficult aspects of urban warfare.
Cities experience limited lines of sight, close-quarters fighting and poor communications, with radio signals traveling poorly between tall buildings. Tunnels make all of these things worse. Even the most advanced drones cannot see underground. Navigating via GPS is impossible. Radio signals for communication do not penetrate far.
The experience of British soldiers involved in a recent tunnel exercise in Leeds, a city in the north of England, highlighted the challenges that IDF soldiers are likely to face. The total darkness made night vision devices virtually useless, as such devices rely on amplifying the weak ambient light present above ground even at night. Disturbing standing water risks releasing toxic gases into the air. The air is up to ten degrees Celsius colder than above ground. “You realize that unless you are well trained and have been there for a long time, you don’t move quickly,” noted a British soldier during the exercise in Leeds.
The sound of weapons fire is also amplified in an enclosed space, notes Joe Vega, the U.S. military’s top expert on underground warfare. That, he says, is why larger teams are needed to clear tunnels, “because you have to constantly replace people in and out – they just can’t keep up.” The effect, also called overpressure, also causes weapon fire to stir up dust. and dirt, which reduces visibility.
The techniques once used to clear tunnels: America used tear gas in Vietnam; the Soviets offered a variety of chemical agents in Afghanistan — “would probably be considered illegal today,” says Daphné Richemond-Barak in “Underground Warfare,” a book on the subject. (Despite its frequent use against domestic protesters, tear gas is largely illegal in war.)
The IDF is increasingly relying on technology to help. For example, it has remote-controlled ground robots that can search for booby traps or ambushes lying in wait. “Entering a tunnel after a robot has combed through it… makes the situation a lot less stressful,” said a soldier from the IDF’s elite Samur (weasel in Hebrew) tunnel unit, quoted in a recent study. “It lowers the tension and the environment becomes much more sterile.” But technology is unreliable. “. than once a soldier was controlling a robot stuck in a tunnel,” another officer complained. “Now try going inside and pick up a robot that is 400 meters away in a tunnel complex. It’s like running 150 meters where every meter is like crossing a desert for a month.”
In the nine years since Operation Protective Edge, the IDF has invested heavily in tunnel operations; it has introduced new doctrines, techniques and specialized units. It has built its own version of Hamas tunnels for training. The Yahalom Battalion, an elite combat engineering unit that includes Samur, was reorganized, notes Omer Dostri of the Jerusalem Institute for Strategy & Security, a think tank, doubling its size from 400 to 900 men and adding new tunnel reconnaissance units to the IDF’s Gaza Division.
It faces a difficult task. On October 16, Lieutenant General Herzi Halevi, the IDF chief of staff, vowed to “enter Gaza, go to the places where Hamas is preparing, acting, planning, launching” and “attack them everywhere, every commander, every agent, destroying infrastructure.” In practice, identifying, clearing, and collapsing hundreds of miles of underground habitat will take years—not weeks or months.
© 2023, The Economist Newspaper Limited. All rights reserved. From The Economist, published under license. Original content can be found at www.economist.com
