With mapping robots and explosive gel: how Israel is waging war against Hamas tunnels

After locating what they described as the entrance to a Hamas tunnel beneath an evacuated hospital in northern Gaza, Israeli army engineers filled the passage with explosive gel and triggered the detonator.

The explosion engulfed the building and sent smoke billowing from at least three points along a nearby road in a neighborhood of the town of Beit Hanoun, surveillance footage showed.

“The gel expanded and exploded, even though they were waiting for us in the tunnel,” an army officer told reporters during a briefing at the Zeelim ground base in southern Israel .

Clearing the tunnels is a major part of Israel’s military campaign against Hamas in the Gaza Strip, in response to the Palestinian militant group’s deadly attack on southern Israel on October 7.

When not using munitions to map the bunkers, manholes and tunnels that both sides say stretch hundreds of miles beneath Gaza, the army opts for tracked robots and other remote-controlled technologies.

The officer could not be identified under briefing rules and declined to provide further details about the underground fight, which he said was a work in progress. He did not mention the name of the Beit Hanoun hospital.

“I think other methods are being developed,” he said. “This is where creativity and innovation come in handy.”

In Beit Hanoun, where his forces were operating, gunmen attacked the Israeli army from tunnel shafts and were killed, he said.

Israel’s policy, he explained, is not to send personnel in the other direction to confront Palestinian fighters who would have the advantage of defending themselves in the narrow, dark, poorly ventilated and foldable ones they know.

“We don’t want to go there. We know they left us many secondary bombs (improvised explosive devices),” he said.

One of the bombs, placed in the lid of a tunnel access shaft at ground level, killed four special forces reservists last week.

Hamas has tunnels for attacks, smuggling and storage, according to security sources. Dozens of shafts can lead to each tunnel at depths of between 20 and 80 meters.

Destroying a well is relatively easy and quick, the officer said, adding, “Any platoon can do it.”

The Israeli military reported last week that 130 wells had been destroyed so far, but did not give figures on the number of tunnels demolished.

The tunnels are more difficult to access. The official said several tons of explosive gel – about which he declined to give technical details except to say it is transported by truck – are needed for a few hundred meters of tunnel.

After-action review is difficult. The officer said about half of the wells in his Beit Hanoun area of ​​operations had been destroyed, but acknowledged they could be rebuilt.

“It is difficult to say how many tunnels (are destroyed) because they are all connected,” he said.

Hamas has denied using hospitals to cover such tunnels. He rejected Israel’s claims that it has a command center located under Gaza’s largest hospital, Al Shifa, which Israeli forces entered on Wednesday.

Hamas took about 240 captives back to Gaza in the Oct. 7 attack that killed about 1,200 people, Israel said. One of the few freed hostages said she and at least two dozen others were held in a tunnel.

The army official said precautions were being taken not to endanger tunnels that could contain hostages.

“Sometimes we get hints that (a target) might be linked to hostages. And then we know not to attack it unless we get approval (that’s clear),” he said.

Like much of northern Gaza, Beit Hanoun is devoid of civilians, who fled south on Israel’s orders when it sent ground troops to try to root out Hamas.

“The only population left are the terrorists,” the officer said, adding that sometimes a secondary explosion caused by the destruction of a tunnel “brings down a building a few hundred meters away.”

Captured Palestinian gunmen have provided Israel with intelligence about the tunnel network, he said, but that information is limited.

“Most of them don’t know the whole city. But they know their own city, they know the tunnel system very well,” the officer commented.

The official said it could take months to destroy Gaza’s entire underground network.

“I think it’s more complicated than the New York subway,” he admitted.