Despite overwhelming military superiority, Israel is struggling to develop an effective strategy to tackle the tunnel network under Gaza.
This “underworld” has provided Hamas with a degree of sanctuary beyond the gaze of satellites, drones and military forces. How will Israel defeat Hamas without destroying the tunnel network?
The “Gaza metro” is bigger in scale than the London Underground network. Many of the tunnels were originally dug in the early 1980s to bypass the border between Egypt and Rafah, enabling the illegal smuggling of trade and weapons.
However, they have since been expanded into two further categories: defensive and offensive.
Since assuming control of Gaza in 2006, Hamas has taken the development of the tunnel network to a new level.
The soft sandstone under Gaza is conducive to tunnelling, but Hamas has also adapted the network in response to Israel’s various attempts to destroy it.
Bunker buster bombs could penetrate deep underground – and if they did not destroy a tunnel directly, the shifting sands would cause nearby tunnels to implode.
By digging the tunnels deeper – the main network is now over 20m (65ft) down rather than around 10m (32ft) for the original tunnels – Hamas made them far more difficult to target and destroy.
They have also been lined with reinforced concrete.
Tunnelling is not a new concept. Over 2,000 years ago, Jewish rebels used tunnels to revolt against Roman rule, and Viet Cong fighters exploited an extensive underground network in its (ultimately successful) war against US forces in Vietnam.
Most dynamically, it was in the First World War that tunnels were used to try to break the stalemate, where professional tunnelling engineers burrowed under enemy positions and used huge quantities of explosives to devastating effect.
Hamas has long recognised that the tunnel network could provide an asymmetric advantage over its Israeli enemy, and by 2021 it claimed to have established a network over 500km (310 miles) long, which has provided a sanctuary away from Israel’s military might.
The Israel Defence Forces (IDF) claim to have discovered over 800 access shafts into the tunnel network, and it has destroyed or sealed over 500.
However, the tunnel network itself is too dangerous for the IDF to clear, so for now, it remains an underworld dominated by Hamas, Sky writes.