Israeli efforts to flood Hamas tunnels recall US woes in Vietnam

Israel is pumping thousands of litres of seawater into Hamas tunnels in Gaza, igniting concerns that hostages who may be held underground could be at risk.

According to Hamas, 500km of tunnels – known as the “Gaza metro” – have been built. Other estimates put the length of the complex at about 250km.

It is not the first time the tunnels have been partly flooded. Egypt used the same tactic in 2015 to destroy tunnels used for smuggling on its border.

More than 50 years ago, during the Vietnam War, the US and its allies struggled against tunnel complexes used by Vietcong fighters, spanning hundreds of kilometres.

Like Israel in Gaza, US forces in Vietnam used bombs with delayed fuses that burrowed into the ground, creating shock waves to crush the structures. But the tunnels continued to frustrate US offensives.

Efforts involved pumping tunnels with explosive gas and tear gas, flooding them, defoliating areas above ground with carcinogenic herbicides and bulldozing stretches of jungle.

Specialist volunteers, the Tunnel Rats, were sent into the complexes armed with torches and pistols.

Today, Israel has Yahalom, a part of its Combat Engineering Corps, the equivalent of the US Army Corps of Engineers who fought in the tunnels in Vietnam. Within Yahalom, Israel has the Samur, or “weasel” soldiers – their own Tunnel Rats.

The US effort in Vietnam took two years, suggesting Israel will not achieve its war aims soon against Hamas tunnels that could be sturdier and deeper underground.

Tunnel warfare, fought in darkness in cramped spaces where even night vision devices do not work and booby traps are a constant threat, minimises advantages for attackers.

Israel has some options that were unavailable to the US in Vietnam, including armed drones like the Lanius, which co-ordinates with a ground-level robot.

But it is not clear whether such systems can cover kilometres of tunnels.

“The largest VC tunnel system by far was in Ben Cat and Phu Hoa districts north of Saigon – no other part of South Vietnam had a tunnel system even remotely as complex,” said Erik Villard, a US army historian specialising in the conflict.

“The tunnel system in the Iron Triangle [an infamous Vietcong base area] was a triangle around 15km north to south and about 7km wide. There was another tunnel system in neighbouring Phu Hoa district that was rectangular, about 15km long and 8km wide.”

The US launched two huge military operations to clear these complexes, one of which – Operation Cedar Falls – was the largest of the war, involving 30,000 US and allied troops.

“Most of the tunnels were packed earth with some wood reinforcements, occasionally multilevel, but mostly a warren of single level tunnels relatively close to the surface,” Mr Villard said.

By contrast, Hamas’s tunnels are built with prefabricated concrete.

Despite often being crudely built, the tunnels proved difficult to destroy, and contained provisions and facilities to sustain forces for months.

Asked if Hamas could hold out in the tunnels for that long, security analyst David Hartwell said: “It’s a tough question because only the Israelis have enough intelligence on their extent and complexity.

“Given how long Hamas has been preparing for this though, nothing would surprise me.

“I doubt [Israel] can destroy them all in the remaining time they’ve got, so it’s more likely to be a case of putting them beyond use and then leaving their long-term destruction to any follow-on non-Hamas administration.”