How Israel trains introverted ‘weasels’ to crack down on Hamas’s tunnels

‘I have been in the tunnels, and once you go down you very quickly lose all sense of direction and all sense of time’

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Part of Israel’s ground invasion of Gaza will involve finding and destroying a vast network of underground tunnels that Hamas has been digging for decades. Here’s what to know about the ‘metro,’ as the Israeli Defence Force sometimes calls it.

How extensive is the tunnel network?

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The tunnels under Gaza have been estimated at between 250 and 500 kilometres in total length, but no one is certain. In 2021, the Israeli Defence Forces said they had destroyed more than 100 kilometres of the network, but Hamas kept building more.

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That same year, Gaza’s Hamas leader Yahya Sinwar claimed that Hamas had 500 kilometres of tunnels in the Gaza Strip and that only five per cent of them had been damaged in recent clashes.

Are the tunnels all the same type?

Experts say there are several types of tunnels. Along the northern border with Lebanon, Hezbollah used diamond-tipped drills to cut passages into rock.

On the southern border, tunnels from Gaza into Egypt have long been used to smuggle goods, while tunnels into Israel have been used for attacks on Israeli villages and, in 2006, to kidnap Israeli soldier Gilad Shalit.

Then there is the labyrinth beneath Gaza, an extensive, complex and sophisticated network, with long passages zigzagging at different depths beneath population centres.

Why are the tunnels important to Hamas?

Their strategic value goes back decades. The first time Hamas used the tunnels for an attack on Israeli targets was in 2001, a few weeks after 9/11, when it exploded a bomb under an Israeli military post.

Then in May 2014, Israel foiled a major Hamas incursion into Israel from the tunnel system. Eado Hecht, a defence analyst at The Begin–Sadat Center for Strategic Studies, told NBC News that if Israel had not stopped the attack, hundreds of Israeli civilians could have been killed. Israel said the reason it launched an attack on Gaza a few months later was to destroy the tunnels.

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Experts believe that in the attack of Oct. 7, Hamas fighters emerged from multiple tunnel exits just shy of the security fence around Gaza before pouring into southern Israel. They suspect Hamas must have breached or turned off the billion-dollar sensor barrier that Israel built to stop it from digging tunnels into Israel, because fighters kept emerging after the military said the area near Gaza was secure.

How old are the tunnels?

Some short, shallow tunnels used for smuggling date back as far as the 1960s, but such early efforts were simple and prone to collapse. Since then, the tunnels started being braced with wooden planks, then metal and concrete. “It’s not like your children would do with their shovel. It was professional,” former IDF officer Achiya Klein told NBC.

How dangerous are the tunnels?

Military experts call them a soldier’s nightmare, and caution against entering the stuffy, narrow passages, which are low on oxygen but full of twists and turns.

Many of the high-tech advantages Israel enjoys above ground disappear when soldiers go underground. Regular night vision goggles don’t work, communication is limited, and soldiers must bring their own oxygen supplies, respirators and chemical protective masks.

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“It’s like being underwater,” according to retired U.S. Army Lt. Gen. Mark Schwartz, who ran U.S. security co-ordination in Israel and the Palestinian Authority from 2019 to 2021.

Experts say soldiers who enter tunnels can quickly lose their bearings and some fall victim to vertigo, and passages can become so narrow that it’s almost impossible to turn around.

“I have been in the tunnels, and once you go down you very quickly lose all sense of direction and all sense of time,” said Daphné Richemond-Barak, an assistant professor at Israel’s Reichman University who founded the International Working Group on Subterranean Warfare and is considered to have written the most comprehensive book on the subject. “The consensus is that you only really send your soldiers in the tunnel as a measure of last resort, maybe to get hostages.”

What is Israel doing to destroy the tunnels?

Since 2004, the IDF has had a sub-unit dedicated to entering, clearing and destroying tunnels. Part of Yahalom, the special forces unit of the Combat Engineering Corps, the tunnel sub-unit is called Samur, the Hebrew word for “weasel.”

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Soldiers who can tolerate the claustrophobic environment inside the tunnels are recruited to become “weasels.” IDF has determined that the best candidates for the job are those who are introverted and “disconnected.”

An officer explained that it takes a soldier “who can make that psychological distance from the situation … You have to be able to distance yourself, to turn inward.” A tunnel soldier compared himself to a fighter pilot: “Really, with all the gear you have to know how to operate; it’s … more complicated than operating an aircraft.”

How can the tunnels be destroyed?

In 2014, Israeli soldiers fought their way to the entrances, clearing booby traps, then searched each tunnel to find more branches and entrances. After each tunnel was cleared and mapped, IDF soldiers used about 10 tonnes of explosives per tunnel to destroy them.

The current operation is expected to use ground robots and drones that will go in first and map what’s ahead. Soldiers will follow.

“Israel is going to have to take out significant parts — maybe not 100% of the tunnel system” under Gaza, Richemond-Barak told NBC. “They have to take down this infrastructure while minimizing the harm to the civilian population. It’s a very complex riddle.”

He added that any successes may be only temporary. “You don’t destroy a tunnel; you damage a segment,” said Joel Roskin, a geomorphologist at Israel’s Bar-Ilan University and an IDF reserve major. He added that tunnels can be resurrected. Or people can dig new ones.

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