Analysis: How would Israel find, map, take and keep Gaza’s tunnels?

Surviving inside

For practical purposes, everything has been analysed so far assuming that there is no opposition in the tunnels. That is completely unrealistic: Hamas has surely prepared to put up fierce resistance.

Most tunnels are probably booby-trapped with pre-positioned improvised explosive devices (IEDs). Those can be wired to remote detonators, but they can also be triggered by specialised detonators that react to light, vibration, noise, movement, and even increased carbon dioxide concentration when people are present.

The tunnels are laced with wires and cables that carry electricity, internet, telephones and military lines. Hamas may have observation and detection devices that would let them know where the Israelis are so they can remotely explode charges in that exact spot.

Israelis cannot simply cut all the wires because, like in movies, some detonators might be triggered when their electrical supply is severed. As everyone with a connection to mining knows, explosions in confined tunnels are far deadlier than on the surface. They spread further and suck out oxygen so those who survive the initial blast often suffocate.

Forcing Hamas out

Every commander, on both sides, prefers to avoid fighting in tunnels. Hamas probably cannot prevent Israelis from entering some tunnels but can try to deny them the freedom to operate in them.

Israeli command knows that its advantage in technology and weapons is considerably higher on the ground than under it, so it would prefer to flush Hamas out and fight on the surface. To do so, it may use chemical agents such as teargas, a little of which goes a long way in tight tunnels.

It is likely Hamas does not have enough protective gear for its tunnel fighters, so any gas-based agent could be effective. Even though Israel does not feel constrained by international conventions, as it does not regard Hamas as a legal combatant, I do not think it would use lethal gasses. That would cause additional international accusations that would be hard to deny.

Water has often been used in the past to flood tunnels and force their occupants out but there is simply not enough water in Gaza. But there may be other options. Egypt is said to have poured sewage into smuggling tunnels from Gaza.

Fighting

Urban fighting is difficult, requiring specific knowledge and equipment; tunnel combat is even more challenging and specialised. As military tunnellers found years ago, ordinary weapons are too big and cumbersome to use in confined spaces.

American Tunnel Rats in Vietnam often only used pistols but found that, when they fired, the flash destroyed their night sight for a long time. When using night vision goggles the problem is even worse, so it is likely that Israelis will carry smaller calibre weapons with sound suppressors, not so much to decrease noise as to prevent muzzle flashes.

Whatever firearms they choose, tunnel fighters will have limited firepower as only two can fire at a time, one kneeling, the other standing over them, blocking the field of fire for the rest of the team.

Hand and rifle grenades are almost certainly out, as well as any kind of rocket launchers. Stun and flash grenades might give the Weasels an advantage by rendering the enemy temporarily deaf and blind, but it is questionable if those can be used without danger to their own side.

In line with centuries-old practice, they will certainly be equipped with combat knives or machetes, as hand-to-hand fighting is certain to happen. There has been much talk about Israeli tunnelling attack dogs, but a military and police canine expert I talked to dismisses the idea.Dogs are far too unpredictable in conditions of extreme combat stress and there were many cases when under flashes and noise of a firefight they turned against their own side, he explained.

Destroying tunnels

Hamas needs the tunnels and might only want to block some of them tactically but not destroy them altogether using small explosions to prevent the enemy from using a particular tunnel.

Digging under combat conditions is impractical and makes the diggers vulnerable the moment the obstacle is removed, so a blocked tunnel is likely to remain so for the duration of conflict. Israeli combat engineers had announced that they were testing a “sponge bomb”, a device containing two chemical substances that create rapidly expanding foam.

The idea is to instantly create a concrete-hard plug to block the tunnels, but there were mishaps in use, and it is not certain if the sponge bomb is ready for deployment. Rather than just block it, Israel wants to destroy every tunnel it takes, so it will have to make sure that the entire structures are caved in, not just the entrances.

In most cases, this cannot be done by simply placing explosives inside tunnels. For more permanent demolition, it is usually necessary to dig deep holes in tunnel walls and ceilings, fill them with blasting dynamite and detonate so that deep structure is shaken and soil caves in to fill it.

It looks quite implausible to embark on such a massive engineering undertaking during fighting, so Israel might see its task as first destroying Hamas fighters and then demolishing their entire underground network.