Security forces discovered a “terror tunnel” inside Israeli territory coming out of the southern Gaza Strip just over a week and a half ago, the Israel Defense Forces revealed on Monday morning.

The concrete-lined tunnel has since been “neutralized,” an army spokesperson said, but would not elaborate on whether it was destroyed or merely sealed off.

Its exact location is still being under wraps by the military censor, though it does not appear that the tunnel led directly into Holit or Sufa, the Israeli communities closest to the southern Gaza Strip.

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The IDF has identified the Hamas terror organization as the group behind the tunnel’s construction and maintains it was dug “in order to carry out attacks against civilians,” a spokesperson said, though he would not discuss what specific intelligence led to that finding.

It is the first such tunnel discovered inside Israeli territory since the end of the war in the Gaza Strip in the summer of 2014. During that operation, dubbed Operation Protective Edge in Israel, at least 34 tunnels were discovered and destroyed by Israeli forces.

Following the operation, Hamas vowed to continue using tunnels and rockets to attack the Jewish state. Speaking at a rally in the Gaza Strip last week, Hamas leader Ismail Haniyeh again told residents: “Our message to the prisoners is a message inked in blood. The rifle and the tunnel are our commitment.”

In response to the discovery, Hamas claimed the tunnel was “old,” one that had been built prior to the 2014 conflict, according to Palestinian media.

The IDF, however, denied that claim, saying it was “a new tunnel that had been built recently.”

The tunnel was located approximately 100 feet (30 to 40 meters) below ground and extended “tens of meters into Israel.” It had been fortified with concrete slabs and featured electrical lines and a rail system, IDF spokesperson Lt. Col. Peter Lerner said.

It was discovered close to the border fence, he added.

Following the 51-day conflict with Hamas in the Gaza Strip in summer 2014, Israel invested an estimated NIS one billion (some $250 million) toward developing a detection system to locate such tunnels.

The army reportedly used such a system to discover this tunnel, though IDF officials stressed that technology was not the only aspect of the discovery operation, which also included extensive intelligence gathering and “boots on the ground.”

“The search for the tunnels has been at the top priority of the defense network and the IDF, and we have not held back our efforts. Dealing with the issue of tunnels is very complicated, and the State of Israel is the world-leader in the field,” Defense Minister Moshe Ya’alon said on Thursday.

“In the past few months, Hamas has experienced a number of cases of tunnel collapses, diggers who die as they labor and now also this disovery,” he said, presumably alluding to Israel’s alleged tunnel detection and destruction systems.

In February, IDF Chief of Staff Lt. Gen. Gadi Eisenkot hinted at this technology, saying that army had “advanced capabilities” to find Hamas’s tunnels.

“We are doing a lot, but many of [the things we do] are hidden from the public. We have dozens, if not a hundred, engineering vehicles on the Gaza border,” Eisenkot added.

Palestinian media claimed Israel had gotten hold of a Hamas operative who was involved in the tunnels project. Mahmoud Jasser Awad Atawna, 29, who helped oversee tunnels, was reported missing by Hamas a few days ago after residents of the Strip lost contact with him, local news outlets reported.

However, it was not clear if Atawna had turned himself in to Israeli forces or been arrested by them.

“The discovery of this tunnel in recent days is the result of ongoing work,” Southern Command head Maj. Gen. Eyal Zamir said in a statement Monday. “The IDF will continue to use all of the tools at our disposal above and below ground to thwart any attempt to harm the people of the State of Israel or IDF soldiers.”

Defense officials estimate that most of the tunnel was dug before the 2014 war, Army Radio reported Monday.

Ya’alon said later that part of the tunnel dated to 2014, and that new additions had been added, Channel 2 reported.

“The working assumption is that Hamas continues to build [these tunnels]. Our job is to prevent attacks against innocent civilians,” an army spokesperson said.

Though the tunnel was found just over one week ago, news of its discovery was forbidden from publication by the military censor.

The IDF worked alongside other Israeli intelligence outfits to locate the tunnel, Ya’alon said.

“The best of Israel’s forces were involved in the tunnel discovery mission, most of which was conducted far from the public eye, including the IDF, the Shin Bet and the defense industry,” he said.

Last week, Palestinian media reported the presence of at least four Israeli D9 bulldozers operating within the Gaza Strip, flattening land near the border.

According to the Ma’an news agency, those earth-movers had been inside the Strip for the previous 10 days, working under the watchful eye of Israeli drones.

On Thursday, a senior IDF officer told reporters that Hamas has been recruiting fighters and collecting materiel at a “surprisingly” quick pace, though the group was not yet prepared for another conflict with Israel.

However, he declared the terrorist organization would not again drag Israel into a war, and insisted any future conflict would be one undertaken at the initiative of the Jewish state.

According to the officer’s assessment, Hamas now has some 5,000 fighters in its special forces and has also filled out its middle and upper ranks with 25 battalion and brigade commanders, the official said.

The group has also been working tirelessly to replace the thousands of rockets, mortar shells and missiles fired at Israeli targets during Operation Protective Edge.

During the 2014 conflict, 72 Israelis and one Thai worker were killed as a result of Hamas attacks, while over 2,000 Gazans were killed in the fighting. The exact number of dead remains contentious, though the UN puts the figure at 2,251, some 35 percent of them combatants. Israel says the percentage was 50.

Amid fast-rising tensions along the border with Gaza, Israel earlier in the week carried out its largest civilian drill near the Palestinian enclave since its 2014 war with Hamas, Channel 2 reported.

Medics, the fire department and civilian response teams simulated a Hamas incursion into Israeli territory, including an attack on an Israeli kibbutz near the border and the taking of hostages by terrorists. The exercise, which was held at Kibbutz Erez, included troops overpowering the terrorists in the community’s dining hall.

Times of Israel staff contributed to this report.