The tunnel in the northern Gaza Strip is wide enough for a large car to pass through, reinforced with concrete and fitted with electrical wiring. And at least one section of the tunnel — which Israel says is the largest it has discovered in Gaza so far — is within walking distance of an Israeli border crossing.
Israel’s military officials, who took a group of reporters, including two journalists from The New York Times, into the tunnel on Friday, say that its size and complexity show the scale of the challenge they face as they try to wipe out Hamas. The group has built a network of tunnels throughout Gaza that allow it to evade and attack Israeli forces, the military says.
The military arranged the tour as Israel comes under increasing pressure to wind down the most intense phase of the war within weeks to try to limit the death toll; already, the Gazan health ministry says, nearly 20,000 Palestinians have been killed.
The Biden administration envisions Israel transitioning from its large-scale ground and air campaign to one that would involve elite forces conducting more precise, intelligence-driven missions to find and kill Hamas leaders and rescue the hostages seized during the group’s attack Israel on Oct. 7, U.S. officials say.
The size of the tunnel the journalists toured on Friday and its proximity to the borderwas a reminder not just of the challenges that lie ahead for Israel but also its failure to prevent such a structure from being built in the first place.
But the Israeli military’s chief spokesman, Rear Adm. Daniel Hagari, who was among the officials conducting the tour, said it was important to note that the tunnel was proof of Hamas having diverted building materials, especially concrete, away from civilian use.
“This tunnel had been built for years,” he said. “Millions of dollars have been spent on this tunnel, hundreds of tons of cement, a lot of electricity. Instead of spending all of them — the money, the cement, the electricity — on hospitals, schools, housing and other needs of the Gazans.”
The Times agreed to wait until Sunday to publish details of the tour, but there were otherwise no restrictions placed on how the visit would be reported. The journalists were accompanied the whole time and were not allowed to wander farther into the tunnel, with the Israeli forces stopping journalists at about 150 to 200 meters, about 650 feet.
But even in that short section, it was possible to see that the tunnel continued a great distance ahead. Vertical shafts extended down from the main tube, suggesting, Israeli officers said, that the tunnel might be connected to a larger network deeper into the earth.
Two military officials interviewed after the tour say that recently gathered intelligence indicated that Israel has grossly underestimated the size of the underground network. The system, which the army previously estimated was about 60 miles long, is now believed to be closer to 250 miles long, they said.
Those claims and other assertions about the tunnels could not be independently verified.
Hamas, which controls the Gaza Strip, has spent years digging a warren of tunnels beneath the enclave, according to Israeli officials. The network, which they say snakes below dense residential neighborhoods across much of the strip, is a veritable subway system for the militant group, which uses the labyrinth to hide and transport weapons and fighters.
The tunnels have been a primary target for attacks since Israel declared war on Hamas in the wake of the Oct. 7 assault on Israel that killed an estimated 1,200 people. But as international anger at civilian deaths in Gaza grows, some Israeli officials say they have been trying to come up with alternative ways of destroying the tunnels besides bombing.
In the past month, Israeli military engineers have experimented with pumping seawater into the tunnels in northern Gaza in an effort to force out any fighters hiding there, according to Israeli military officials interviewed after the tour who spoke on the condition of anonymity because they were not authorized to speak publicly about the effort. It is unclear if the technique will work, given the force needed to send water cascading through the system’s multiple offshoots, the officials said.
Besides arranging Friday’s tour, the Israeli military also gave reporters a video that shows men using large earth-moving machines digging a tunnel. The military said it had obtained the video when it raided Hamas offices during its ground invasion. The video shows that the work is being conducted in a large building that looks like a warehouse.
It was unclear where the video was shot, but the Israeli military said that the video showed the construction of the tunnel toured on Friday.
Two officials said Israeli leaders were surprised by the video’s contents because they had not realized that Hamas had access to those types of earth-moving machines, which can more safely and quickly build very large tunnels. Until the discovery of the video, the officials said they thought that only Hezbollah, the Iranian-backed militant group based in Lebanon, not Hamas, could build such large tunnels.
The military said the tunnel where it conducted the tour was the first it had found that was big enough to allow cars or other vehicles to move through.
On Sunday, the military released another video that it said showed a brother of Yahya Sinwar, the Hamas leader in Gaza, being driven in a car through the tunnel. The military said the presence of Mr. Sinwar’s brother Muhammed — who is also considered a top Hamas leader and his brother’s confidant — indicated the strategic importance of this tunnel.
The underground passageways have become a central element of the information war also being fought over Gaza.
Last month, as Israel forces moved to occupy Gaza’s largest hospital, Al-Shifa, which it said was offering cover for a subterranean Hamas base, the militants and hospital officials insisted that the facility was used only to treat patients.
But after Israeli soldiers captured Al-Shifa, they conducted a tour in which journalists were shown a 350-foot section of tunnel and rooms beneath the hospital. The military argued that the tunnel, along with weapons it said had been found in the hospital and security video of hostages being taken inside by armed men, supported its decision to send its troops there.