Fighting in Gaza has entered day 21 after the Palestinian group Hamas launched a surprise cross-border attack on Israel, killing about 1,400 people. Since the October 7 attack, Israel has been bombarding Gaza, in which more than 7,000 Palestinians have been killed.
The Israeli military has also mounted an incursion deeper into Gaza on Friday as it readies for a ground offensive against Hamas. However, one of the biggest challenges the Israeli troops face is an extensive Hamas tunnel network, where the group is said to have taken several hostages.
Hamas reportedly has different kinds of tunnels -- hundreds of kilometres long and up to 80 metres deep -- running beneath the sandy 360-sq-km coastal strip and its borders.
Sponge bombs create sudden explosion of foam
In order to fight Hamas through its tunnel network, Israel is reportedly making "sponge bombs", which create a sudden explosion of foam that rapidly expands and then hardens.
According to a report in The Telegraph, Israel has been testing the chemical grenades, which contain no explosives but are used to seal off gaps or tunnel entrances from which Hamas operatives may emerge.
These devices are said to be encased within a protective plastic container that has a metal barrier that divides two distinct liquids. When activated, these liquids merge and advance toward their intended destination.
The Israel Defense Forces (IDF) were seen deploying these devices during exercises in a mock tunnel system near the Gaza border in 2021.
Among the elite units tasked with going underground is Yahalom, specialist commandos from Israel's Combat Engineering Corps known as the "weasels", who specialise in finding, clearing, and destroying the tunnels.
How Hamas built its tunnel network
Hamas was created in Gaza in 1987 and reportedly started digging tunnels in the mid-1990s.
The tunnel network is a key reason why Hamas is stronger in Gaza than in the Israeli-occupied West Bank.
Tunneling became easier in 2005 when Israel pulled its soldiers and settlers out of Gaza, and when Hamas won power in a 2006 election.
(With agency inputs)
