Kibbutz Nahal Oz, Israel — The members of this Israeli farming commune remember the gunfire and then hiding in their bungalows. It was the 2014 war with Hamas, and a band of fighters from Gaza had infiltrated Israeli territory through a subterranean tunnel that reached to the wheat fields just beyond the kibbutz perimeter fence.

Though they never made it to the kibbutz houses, the Palestinian commandos killed five soldiers — highlighting Hamas’ use of tunnel warfare as an effective new tactic in the lopsided battle against Israel.

By the end of the month-long war, Israeli generals and politicians said they had destroyed all of Hamas’ cross-border attack tunnels. But a year and a half later, the same problem seems to have returned: Hamas leaders in Gaza are talking about rebuilding the tunnels, and Israeli security chiefs are acknowledging — both to the press and residents — that tunneling efforts continue.

“[The army] is telling us that the handling of the tunnels wasn’t good enough. They didn’t realize there were so many and so well built,” said Yael Raz Lachyani, a 39-year-old mother of three and the head of the Nahal Oz emergency response team. “They tell us, ‘Don’t worry, we have a solution.’ What the solution is, they can’t tell us.”

Standing alongside an old watchtower and a military listening post, Lachyani looks through a perimeter fence of concertina wire and chain fence, across a field of wheat to the gray cinder-block buildings in the eastern Gaza City neighborhood of Shujaiyeh. The Israel Defense Forces leveled the neighborhood in 2014 searching for Hamas fighters. “It’s 800 meters [half-mile] between the houses. Every house has a mortar launcher. They can see our houses very clear. They are probably watching us right now.”

At the end of the war in 2014, the army said that it had destroyed some 10 cross-border tunnels that Hamas had hoped to use to launch raids on border communities like Nahal Oz or kidnap Israelis back into Gaza. Prime Minister Benjamin Netanyahu declared the anti-tunnel operation one of the main achievements of the war.

Within months after the end of the fighting, reports started emerging that Hamas was once again working on the tunnels. The renewed activity reportedly sparked a debate within the Israeli army about whether or not the military should launch limited invasions of the Gaza Strip to destroy the new tunnels.

Last week, Hamas acknowledged losing members of its military wing in accidents, part of the effort to rebuild the underground network. Meanwhile, recent footage of the border region showed army combat engineers using construction excavators to try to uncover the tunnel routes. A report on Israel’s Walla! News this week asserted that the army is currently experimenting in the border region with a new high-tech solution to locate the tunnels. Israeli government ministers acknowledged in the last week the tunnel challenge still exists.

“Ultimately, you can’t completely seal your border. There’s no comprehensive defense,” said Israeli Energy Minister Yuval Steinitz in a town-hall meeting in Beersheva. “Indeed there are threats. Israel doesn’t necessary know about every tunnel and every entrance.”

The media attention has made the tunnels into a political football for rivals to the right and left of Netanyahu, who is being accused of inaction in the face of a threat. In contrast to Steinitz, Naftali Bennett, leader of the pro-settler Jewish Home party, is taking a more aggressive approach, reportedly calling for a preemptive strike against the tunnels. Opposition leader Isaac Herzog of the left-wing Labor Party said Israel should bomb the tunnels.

“It’s a threat that is a top priority for the IDF,” said army chief of staff Lt. Gen. Gadi Eisenkot on Tuesday, who added that 33 underground channels were destroyed in 2014. “Our enemies have not abandoned this. Despite reconstruction efforts, Hamas has chosen to direct considerable resources to refurbish what, in their eyes, is a [tactic] that creates a balance [of deterrence] with Israel.”

Tunneling has been used for millennia in warfare, from the Vietnam War, to World War I, and all the way back to the Roman era and the Jewish Revolt. Hamas operatives used a tunnel in a 2006 border strike in which soldier Gilad Shalit was kidnapped into Gaza. Hamas has turned to tunneling because it has become the most effective method of psychological warfare against the Israeli population: Israeli fences have blocked suicide bombers and Israel’s Iron Dome anti-rocket system is protecting cities from Katyusha attacks.

In 2014, it was the war against the tunnels that forced the Israeli army to cross the border into Gaza, where it suffered much of its casualties, said Eado Hecht, a researcher in military doctrine at Bar-Ilan University’s Begin Sadat Center. Until Israel finds an Iron Dome-like solution for the tunnels, Hamas will continue to have a tactical advantage on the border, Hecht said.

“This is what they are looking for,” he continued. “They are hoping for increasing number of casualties to force a concession and achieve a change in [Israeli policy]. If we can manufacture a detection device, that will change the game. Until then, it will [continue to] be like 2014.”

That would endanger the future of kibbutzim along the Gaza border like Nahal Oz. The last war almost broke the kibbutz, which was established in 1951. The kibbutz numbered 500 people in 2003, and on the eve of the 2014 war had a population of 400. The fighting and the death of 4-year-old Daniel Tragerman in a mortar attack that fell on his house, spurred an exodus of 17 families. The kibbutz — the most bombarded spot in Israel during the last war — now has a population of 300. “People felt that the kibbutz was about to collapse,” she said.

But Raz Lachyina says that Nahal Oz was able to recruit a crop of young couples and families to move to the kibbutz, and says that it is on the rebound. A new kindergarten that has the reinforcements of a bomb shelter is being completed that will replace the current school, which residents had surrounded with concrete slabs to protect it from rocket and mortar fire. A new kibbutz pub is also going up.

Still, the community has the trappings of a battle front: Even though the war has ended, a detachment of soldiers is stationed on the kibbutz grounds and patrol with machine guns, keeping watch beyond their fence. The mosquito-like buzz of IDF observation drones monitoring Gaza can be heard overhead.

“You’re not just close to Gaza; you’re close to Gaza City itself,” said Amir Tibon, a diplomatic correspondent for the Walla! News website who moved down to the kibbutz from Tel Aviv a year and a half ago with his girlfriend. They live on a lane of mobile homes originally slated for West Bank settlements, but that now house the newcomers.

“You can feel and smell Gaza strongly. You can clearly hear the muzzein calls [for prayer]. What you also hear is Hamas taking the rubble from the war and turning it into bricks.”

Tibon says the fear of the tunnels is worse than the rockets. “It enters your psyche,” he says.