Sponge bomb

Not to be confused with Sponge grenade.

A sponge bomb is a specialized device designed to seal the end of a tunnel. Small enough that it can be set by a single person, it is a non-explosive, chemical bomb that releases a burst of expanding foam that quickly hardens.^[1][2]

Development

The sponge bomb was developed by the Israel Defense Forces (IDF) to address the use of tunnels by Hamas in Gaza.^[3][4]

Design

Housed in a plastic container, the bomb has a metal partition that separates two liquid reagents. Once the partition is removed, the liquids mix and react, causing them to rapidly expand and then solidify, creating a physical barrier blocking the tunnel. The device is either set at its target by an individual or thrown.^[1]

In 2021, testing of sponge bombs was reportedly conducted by IDF in simulated tunnels.^[5]

During initial testing of these bombs, the liquid emulsion was found to be hazardous to work with when mishandled – some Israeli soldiers lost their eyesight.^[1]

Historical perspective

This is not the first time that sticky foam has been used by a military force. Reportedly, the U.S. Marine Corps and the U.S. Army have used streams of foam as non-lethal tools for crowd control or restraint of hostile combatants.^[4]