LONDON: Israel is preparing to use novel ‘‘sponge bombs’’ in its fight against Hamas through the network of tunnels under Gaza.
The Israel Defence Forces (IDF) has been testing the chemical bombs, which contain no explosives but are used to seal off gaps or tunnel entrances from which fighters may emerge. The IDF has not commented on the use of the sponge bombs, which create a sudden explosion of foam that rapidly expands and then hardens.
Its soldiers were seen deploying the devices during exercises in 2021. The army has set up a mock tunnel system at the Tze’Elim army base near the border with Gaza.
Troops face a bloody battle through the tunnels known as the ‘‘Gaza Metro’’ when they launch their expected ground invasion. The network is thought to be hundreds of kilometres long and dense with traps. It is where Hamas has taken many of the more than 200 hostages and where its leaders will hope to survive the coming war.
The sponge bombs would prevent soldiers being ambushed as they move further into the network, sealing off gaps through which Hamas could attack.
Contained in a sturdy plastic vessel, the specialist devices have a metal partition in the middle separating two liquids. Once this barrier is extracted, the compounds mix as the soldier positions the ‘‘bomb’’ or throws it further ahead.
Specialised teams in the engineering corps have been grouped into tunnel reconnaissance units and equipped with ground and aerial sensors, ground penetrating radar and special drilling systems to locate tunnels.
They have also been issued with special equipment to see when underground.
There are potential complications with the underground arsenal, however.
The sponge bombs – technically a liquid emulsion – are hazardous to work with, and some Israeli soldiers have lost their sight through mishandling the mixture.

Micro-drones for reconnaissance, capable of being held in the palm of a hand, may also be used but will similarly suffer as the radio signal weakens.
The Israel-based Roboteam technology company has developed IRIS, a small, throwable drone that can be driven on large wheels via remote control.
Known by special forces as a ‘‘throwbot’’, it relays images back to a controller, operating the device from a position of safety.
Some devices can have weapons attached so that if enemy combatants are seen, the controller can detonate explosives.
John Spencer, a former US major who chairs urban warfare studies at the Modern War Institute at West Point, says subterranean fighting is ‘‘more like fighting underwater than fighting in buildings’’.
‘‘Nothing that is used on the surface works in the same way or with the same efficiency underground.’’
Hamas, a designated terrorist organisation in Australia and the US, has integrated underground warfare into its overall military strategy.
Tunnels, some started decades ago, are integral parts of a wider plan to prepare the ground for ambushing Israeli forces above.
Many stretch under civilian structures, with entry and exit points in dwellings and other nonmilitary buildings, making it extremely difficult for Israel to attack them without inviting international condemnation.
The Telegraph, London
Dominic Nicholls served for 23 years in the British Army with operational deployments in Iraq, Afghanistan, the Balkans and Northern Ireland.