Adel Hana/AP Photo
Israel is said to be pumping seawater into the underground network of Hamas tunnels in Gaza.
The tactic may sound shocking — but it isn't new; Egypt did the same thing at least twice, one using sewage instead of water.
According to The Wall Street Journal, Israel on Tuesday began flooding the approximately 300-mile-long tunnels with water from the Mediterranean Sea.
Its aim appears to be to force Hamas fighters in the tunnels to leave, where Israel can attack them.
Israel believes the tunnel system, nicknamed the "metro," is used to transport weapons and fighters into Israeli territory.
The Israel Defense Forces declined to comment when Business Insider asked whether it was flooding the tunnels. But the tactic has a history.
Egypt, which borders Gaza to the east, had a similar plan in 2013.
It flooded smuggling tunnels connecting Gaza to its Sinai Peninsula, using foul-smelling wastewater.
Mohamed Morsi, Egypt's president at the time, wanted to shut the tunnels to block the flow of weapons and militants from Gaza into Sinai, where an insurgency was underway, The New York Times reported at the time.
The Egyptian military had previously tried pumping gas into the tunnels before switching to sewage, the Times said. It destroyed some two dozen tunnels in the end.
A couple of years later, Egypt started flooding tunnels using seawater pumped from the Mediterranean Sea — almost exactly what the WSJ said Israel is now doing.
Egyptian officials confirmed to Al Jazeera that the water-pumping was underway, saying the operation was aimed at ending smuggling activities.
Egyptian President Abdel-Fattah el-Sisi claimed the flooding of the tunnels was being carried out for security reasons. He said it was coordinated with the Palestinian Authority, the entity which governs the West Bank and used to run Gaza until Hamas took over.
In a joint statement in September 2015, several Palestinian factions condemned the flooding, raising concerns that it would destroy agricultural land and pollute underground water reserves, according to Middle East Monitor.
Similar concerns are being voiced now, with experts saying Israel's seawater tactic could exacerbate water pollution and cause environmental damage in Gaza.
In 2016, Egypt launched another flooding operation.
Yuval Steinitz, an Israeli minister at the time, said that the flooding was partly "due to Israel's request," describing it as a "good solution" for tackling Hamas' network of tunnels.
This time there is an extra risk to consider — whether the flooding may harm some of the 100 hostages taken by Hamas on October 7, who are yet to be freed.
In leaked audio recordings of a meeting with Israeli Prime Minister Benjamin Netanyahu, freed hostages and the relatives of those still in captivity said they feared their loved ones would be killed by the deluge of water, per the Israeli media outlet Ynet.
The Journal reported that the IDF is reluctant to send soldiers underground because of the risk of booby traps.
Instead, the paper said, the army intends to use the flooding method along with airstrikes, explosives, robots, dogs, and drones.
