Hamas's 'Underground World' Surprises Israeli Military

What was discovered in the tunnels under Gaza?

After invading the Gaza Strip, the Israeli army discovered that in recent years Hamas had managed to build a complex and sophisticated system of tunnels. This "underground world" took the Israeli military by surprise, writes Amir Bohbot, a military analyst for the Walla newspaper.

With each passing day, Israel's engineering forces are uncovering more tunnels - and learning more about the "underground city" that Hamas has built under Gaza. The IDF had a map of Gaza's tunnels before 2014 - but it turned out to be out of date.

Engineering officers say Gaza has several underground "rings" of defence. These are divided into two tunnel systems. Closer to the surface is a "tactical" network of underground passages. Deeper underground is the "strategic" tunnel system.

The tactical system consists of conventional tunnels, which the Israeli military calls "shafts". A tunnel may start in a terrorist's home or in a civilian facility - a hospital, a school, an international aid agency for Palestinians. It leads to a military position - a fortification for defence or an infrastructure for an attack on Israel.

Some of the tactical tunnels are very old. But Hamas has not abandoned them, only added signs, markings and tunnel numbers to make them easier for terrorists to navigate.

"The 'strategic' underground system is built deep below the tactical network. This is another layer of tunnels that gives Hamas operatives the ability to move quickly underground, meet at certain points, hide for long periods of time, set up headquarters and control the fighting from there.

There are "highways" among these tunnels - they connect several "mines" and allow terrorists to retreat quickly into the heart of settlements, under dense residential buildings. Or, alternatively, to emerge quickly and attack. Some of the "highways" can reach the centre of Gaza City.

Some of the strategic tunnels connect to what is known as the Gaza Metro - a very large system of deep and wide tunnels connecting the south, centre and north of the Strip, stretching for many kilometres.

Hamas uses part of the strategic system for special tasks, while some of the tunnels are reserved for the high command. Because they are deep, they require supporting infrastructure to operate - for example, to ventilate and pump air into the underground passages (the very fuel Hamas needs, including from Gaza hospitals). Amir Bohbot notes that the IDF is already destroying tunnels and mines at this stage, leaving some to be studied and intelligence gathered.

The Israeli army is looking for a systemic solution to the problem of a vast "underground city", writes Bohbot. In some cases, the IDF is implementing methods to reduce the damage caused by air strikes.