IDF trial of flooding Hamas tunnels with seawater proves successful, ToI told

Spokesman says army has intel on hostages’ location and won’t take steps that endanger them; Hamas official claims terror group’s tunnels engineered to withstand such tactics

Emanuel (Mannie) Fabian is The Times of Israel's military correspondent

A Hamas tunnel discovered by IDF troops in northern Gaza's Salatin, close to Jabaliya, December 7, 2023. (Emanuel Fabian/Times of Israel)
A Hamas tunnel discovered by IDF troops in northern Gaza's Salatin, close to Jabaliya, December 7, 2023. (Emanuel Fabian/Times of Israel)

Israel’s reported attempt to pump seawater into the vast network of tunnels beneath Gaza was a success, The Times of Israel learned Thursday, as the army warned of “new combat methods” to deal with terrorists hiding underground.

The Wall Street Journal reported on Tuesday that the IDF had started pumping seawater into Hamas’s underground tunnel system, a move aimed at destroying the Palestinian terror group’s subterranean network of passages and hideaways and at driving its operatives above ground.

IDF Chief of Staff Lt. Gen. Herzi Halevi said last week that flooding the tunnels was “a good idea” but wouldn’t comment further.

On Thursday, The Times of Israel confirmed that the tunnel flooding had indeed begun, albeit in a limited trial capacity. Still, it was understood to have been a success.

Senior Hamas official Osama Hamdan was asked about the issue on Thursday and he claimed that the terror group’s tunnels were engineered to withstand flooding as well as other “potential dangers.”

Asked about concerns that the tactic might harm the hostages — some of whom are being held in Hamas tunnels — IDF Spokesman Rear Adm. Daniel Hagari said in his own press conference Thursday that the army operates based on intelligence it has regarding where it believes the hostages are located and that it will not take steps that harm them.

Soldiers duck for cover after Combat Engineering Corps troops detonate a Hamas tunnel in the northern Gaza Strip, November 7, 2023. (Emanuel Fabian/Times of Israel)

Last week, the IDF announced that soldiers had discovered more than 800 tunnel shafts in the Strip since the beginning of the ground offensive targeting Hamas that began in late October, some 500 of which had already been destroyed.

Two days earlier, the Journal reported that the IDF had set up five large water pumps near the Shati refugee camp in Gaza City, capable of flooding the tunnels within weeks by pumping thousands of cubic meters of water per hour into them.

It said the method is one out of a few others weighed to tackle the tunnels, including airstrikes, use of liquid explosives and dispatching dogs, drones and robots into the network.

Environmental experts have warned that the move could have long-lasting effects on the groundwater in the Strip.

According to WSJ’s earlier report, opinions within the Biden administration on the flooding tactic have been mixed, with some officials expressing concern while others have said they back Israel’s efforts to destroy the tunnels and that there isn’t necessarily any American opposition.

US President Joe Biden was asked Tuesday about the report.

“With regard to the flooding of the tunnels… There [are] assertions being made that there [are] no hostages in any of these tunnels, but I don’t know that for a fact,” Biden said.

Among the concerns cited by the newspaper were potential damage to Gaza’s aquifer and soil, if seawater and hazardous substances in the tunnels seep into them, as well as the possible impact on the foundations of buildings.

In 2015, the Egyptian military flooded several smuggling tunnels beneath the Gaza Strip’s southern border.

Separately on Thursday, the army released footage showing Hamas operatives shot dead in a tunnel by forces from the IDF’s elite Yahalom combat engineering reconnaissance unit.

“In the Hamas tunnels, the troops planted explosives… we identified the terrorists with a camera and killed several terrorists in this incident,” Hagari said during a Thursday briefing.

“Hamas terrorists, especially its senior members, choose to hide underground. This is the Hamas method of operating, hiding while using the civilians above them as human shields,” he said, warning that the army has “new combat means” to kill Hamas operatives in its tunnels.

“We will enter, plant explosives in the areas where the terrorists are, and we will wait for the right moment to kill them underground. The terrorists will not be safe underground,” he added.

The footage appeared to show a camera being lowered into the tunnel, with one operative touching the device, before apparently being shot or being hit by an explosive. The video then cuts to another clip, showing the bodies of several Hamas operatives on the floor of the tunnel.

Times of Israel staff contributed to this report.

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