Sponge.

This is coolbert:

Secret weapon counter-measures Israel the Hamas tunnel complexes. SpongeBob SquarePants?

"How Israel Plans to Use “Sponge Bombs” in Ground Raids to Fight Through Hamas' Labyrinth of Tunnels"

Go see the You Tube video:

"The Israel Defense Forces (IDF) has been testing a secret chemical bomb to be used in the war against Hamas, as per a report. Israeli forces plan to use novel 'sponge bombs' in battles through the network of Hamas tunnels in the Gaza Strip, The Telegraph reports. 'Sponge bombs' are said to have no explosives but can be used to seal off gaps or tunnel entrances from which Hamas fighters may emerge."

The Israeli will not only want to clear the tunnel complexes of Hamas, they will want to destroy them as well. Render them useless the underground labyrinth out-of-action using the "secret chemical bomb" to do so!

See from a Quora question and answer a discussion of the "challenges" as posed to American military forces in Vietnam their efforts to destroy or make ineffective the tunnel system of the Viet Cong during the Second Indo-China War.

"The logistical challenges were daunting, even for the U.S. military . . . to destroy a 500-meter [yards] tunnel required:

* 10 double generators

* 300 pounds of calcium carbide 

* 50 gallons of water, weighing 400 pounds

* 9 forty-pound cratering charges

* 4 boxes of military dynamite

* 665 pounds of explosives"

Sponge bombs the latest technological advancement will make the Israeli efforts to defeat the Hamas subterranean fortress possible? Denial equates to destruction?

coolbert.