UPDATED
THERE IS NO HIGHER PRIORITY for intelligence services in a war than locating the enemy. That’s why “find” is the first word in the combat mantra of “find, fix and finish.”
For the intelligence officers helping the Israel Defense Force plan its ground invasion of the Gaza Strip, the first piece of business is to map the vast complex of underground tunnels that provide shelter for Hamas’s military leaders and weapons stores, not to mention the 220 hostages held by it and other militants.
An Israeli army officer shows journalists a tunnel reportedly used by Palestinian militants for cross-border attacks from Gaza into Israel, July 25, 2014. (Reddit)
And now, thanks in part to 85-year-old Yocheved Lifshitz, an Israeli hostage who was released earlier this week, we now have confirmation that the tunnel system is as vast and daunting as reputed, an elaborate underground fortress that provides Hamas fighters with formidable defensive and offensive advantages now that what looks like a first phase of Israel’s ground operation has begun. Under a heavy barrage of artillery and air strikes, Israeli tanks and ground troops moved into the town of Beit Hanoun in the northern Gaza Strip late Friday night, sources in Israel told SpyTalk.
“They brought us to the entrance to the tunnels,” Lipshitz told a news conference at a Tel Aviv hospital soon after her release. “We arrived in the tunnel and walked for kilometers on wet dirt. There is a giant system of tunnels, like spiderwebs. . . .We started walking in the tunnels, the dirt is damp and everything is always damp and humid. We reached a hall with 25 people in it. . . They guarded us closely.”
With the captives most likely separated into small groups and being held in different tunnels, the Israelis will have to pinpoint their exact locations and try to rescue them before the army can destroy Hamas’ subterranean redoubts. And to do that, Israel’s use of sophisticated ground-piercing surveillance technology may determine both the fate of the hostages and the outcome of the battle.
A person familiar with the technology says Israel has advanced hyperspectral sensors, which can confirm the presence of people, weapons, explosives and other objects deep beneath the ground, among other things.
Hyperspectral sensors use a vast portion of the electromagnetic spectrum to analyze and identify objects buried beneath the ground or under the water. They operate on the principle that all materials leave unique fingerprints in the electromagnetic spectrum. These sensors, first developed by NASA in the 1970s, scan these fingerprints, known as spectral signatures, and identify the materials that make up the scanned object.
Geologists were the first to use hyperspectral sensors to find subterranean oil fields and mineral deposits. Since then, their utility has spread to farmers, who use the sensors to track the development and health of crops, and to environmentalists, who use them to aid in recycling by their ability to identify different types of plastic. They’re also used in medicine and food processing,
But these sensors also can read subterranean soil densities and the signatures of other buried materials, such as concrete and metal rebar, which would permit the Israelis to pinpoint the exact location of underground tunnels. They also can identify the spectral signature of the weapons and explosives that Hamas stores in their tunnels. And the sensors can pick up the chemical fingerprints of subterranean carbon dioxide, a sure sign of people—both Hamas fighters and hostages—living underground.
This person said Israeli drones outfitted with these sensors can linger over Gaza collecting data on what lies beneath the surface. The army then downloads that data to a receiver close by inside Israel or aboard an Israeli naval vessel offshore.
But this person cautioned that hyperspectral sensors have their limits: They cannot penetrate any tunnel segments that Hamas has reinforced with concrete or metal rebar. And the sensors can’t distinguish between Hamas fighters and hostages.
“These sensors can tell if there’s a person or persons in those tunnels, but they can’t tell if it’s Ibrahim or Abraham,” this person, who asked not to be identified, told SpyTalk.
A Vast Labyrinth
Hamas began digging tunnels under Gaza’s border with Egypt in 2006 to smuggle in food and fuel in defiance of a combined Israeli-Egyptian blockade. Over the ensuing years, Hamas expanded the tunnels into a vast, labyrinthine network, zig-zagging beneath the coastal Palestinian enclave for hundreds of looping miles and connecting Gaza City with other towns and refugee camps in the strip.
According to Daphne Richemond-Barak, an Israeli expert on subterranean warfare, the Gaza tunnel complex became a core element of Hamas’ military strategy, allowing the group to move its missiles quickly between different firing positions and thwart Israeli reconnaissance and retaliatory strikes.
“They just pop up out of the ground when they launch rockets, and then they go back in,” she said in a recent podcast produced by West Point’s Modern War Institute. The subterranean complex has been compared to the legendary tunnels of Cu Chi, a vast network that communist guerrillas dug right under U.S. forces and parts of the capital of Saigon during the Vietnam War.
It was during Israel’s 2014 war against Hamas that the Israeli forces discovered just how intricate, sophisticated—and lethal—Hamas’ tunnel complex had become. Richemond-Barak said the soldiers who entered Gaza during that conflict found several levels of tunnels equipped with electric lights, air ventilation and water pipes, with some walls and archways reinforced with concrete and metal.
On one level, she said, there were command-and-control centers and storerooms for missiles, launchers and other weapons; on another, dormitories with stores of food and bedding for fighters. The average depth of the tunnels was 160 feet below the ground, but some ran as deep as 230 feet. Others had been outfitted with rails to facilitate the transport of cement.
Israeli military officials referred to the subterranean complex as the “Gaza Metro” and announced in 2021 that their air strikes and tanks had destroyed some 60 miles of tunnels. But Richemond-Barak said the human cost of gathering that intelligence was high, and Hamas quickly dug new tunnels to replace those Israel had destroyed.
“They had a big wake-up call in 2014, when the Israel Defense Forces had to send troops into the tunnels,” she said. “They were really unprepared; they didn’t have the right equipment; they hadn’t gone through the proper training. They really didn’t know what they were doing, and there were a lot of casualties.”
Since then, Richemond-Barak said, “Israel has had nine years to up its game.”
Upping Israel’s Tunnel Warfare Game
U.S. Army combat veteran John Spencer, who chairs the urban warfare program at the Modern War Institute and has studied the evolution of Israel’s tunnel warfare skills, used a recent series of podcasts and articles for the institute’s Urban Warfare Project to outline some of the specialized tunnel warfare units, intelligence-gathering technology and tactics that Israel has developed since 2014 and will likely deploy for its looming Gaza invasion.
At the point of Israel’s tunnel warfare spear is the Combat Engineering Corps’ elite Yahalom commando unit, whose soldiers specialize in finding, clearing and destroying tunnels. While its size is classified, Spencer said Yahalom is one of the largest units in the world focused on underground warfare. He added that tunnel warfare training is now included in basic infantry training for nearly all IDF combat units.
“The tunnels don’t just complicate things; they change the very nature of the fight,” said Richemond-Barak. “They change the way you have to think about building the invasion at the operational level. They change the kinds of soldiers you can send. And they put your forces into harm’s way at an unprecedented level.
Yahalom commandos carry a toolkit of specialized gear for their subterranean operations, including ground-penetrating radar, drilling equipment and the hyperspectral sensors to find the tunnels and identify who or whatever might be in them, Spencer said.
Once a tunnel is located, Yahalom’s subordinate Samur unit is called in to enter, clear, map and finally destroy the underground passageway. Samur’s specialized equipment includes radios, navigational gear and thermal night vision goggles that work underground, as well as a suite of flying and ground robots that can map tunnels without endangering the Samur soldiers. The ground robots are armed with remote-controlled machine guns or grenades to fend off Hamas defenders.
The Israeli army’s Oketz canine unit also provides Samur commandos with dogs specially trained for underground operations.
In addition, Israeli special forces units including the army’s Sayeret Matkal and Yamam, respectively Israel’s equivalent of the U.S. Army’s Delta Force and the Navy’s SEALS, train with Yahalom soldiers to learn best practices for handling underground threats.
To destroy tunnels, Samur commandos can call in air strikes to drop so-called “bunker buster” munitions such as the GBU-28, which can penetrate 100 feet of soil or 20 feet of concrete. Israel also uses a combination of explosives, bulldozers and tanks to destroy or seal off tunnel entrances.
Spencer said Israel is also experimenting with so-called “Sponge Bombs,” which contain two non-explosive chemicals that, when combined, create a dense foam that rapidly expands and hardens. As Israeli troops move through the tunnels, these devices could be used to seal off side passageways to prevent Hamas ambushes, but they also must be deployed with great care, lest they injure the troops themselves.
Hamas Also Has Honed its Skills
But just as the IDF has had nine years to develop its tunnel warfare skills, so has Hamas.
“The hard truth is that the depth and scale of Hamas tunnels in Gaza will surpass Israel’s specialized capabilities,” Spencer wrote in an article titled “Underground Nightmare: Hamas Tunnels and the Wicked Problem Facing the IDF,” that appeared recently in the Modern War Institute’s website.
While Israel’s relentless bombing of Gaza over the past three weeks has killed thousands of Palestinians so far, reduced wide swathes of the heavily populated enclave to rubble and turned an estimated 700,000 people into internally displaced refugees, it’s unclear how much damage the bombs have caused to Hamas fighters or their tunnels.
Spencer predicted Hamas already has hidden countless IEDs in the tunnels to thwart any Israeli hostage rescue attempt.
“It’s a trap,” said Richemond-Barak. “Most military doctrines advise against sending soldiers into tunnels. It has to be a measure of last resort.”
And while she acknowledged that Israel’s tunnel warfare skills have come a long way since 2014, Richemond-Barak forecast Hamas would exact an unbearably high price on Israeli invasion forces in any last stand, both above and below ground.
“When it comes down to it, you have three layered problems—the urban fighting, the subterranean challenge and now the hostages in the tunnels,” she said. “ When you put these three layers of problems together, you end up with an equation that no matter how well prepared you are for this, it’s not a solution. . . . All combined, we’re likely to see a lot of casualties.”
UPDATE: A previous version of the story said that Hamas alone was holding hostages. Other Islamist terrorists are holding hostages, we have been told. This piece has also been updated with news late Friday of an Israeli ground invasion.