The surprising length and level of completion of the Hamas terror tunnel, as exposed by the IDF, on March 21, 2014. Photo: IDF / Twitter.

Israel’s Ministry of Defense is investing millions of shekels in research programs designed to locate tunnels from Lebanon into Israel.

“There is a lot of talk about it and concern,” according to one anonymous source who spoke with Israel’s Channel 2 News on Monday.

Since the IDF’s discovery and detonation of dozens of terror tunnels dug by Hamas in Gaza beneath Israeli territory during the course of Operation Protective Edge, jittery Israelis are wondering if their hostile neighbors to the north, across the border in southern Lebanon, might be planning the same tactic.

The issue first came to the public’s attention during the 2006 war against Hezbollah, when the Shi’ite terrorists popped out of well-concealed, planned and equipped tunnels to attack IDF soldiers – often with lethal results.

A renewed public awareness of the issue emerged when residents of Kibbutz Gesher HaZiv and Kiryat Shmona reported that they heard muffled voices beneath their homes and suspected that tunnels were being dug under their feet, not unlike similar reports from Gaza-area residents.

Last week, Kiryat Shmona Mayor Nissim Malka asked Defense Minister Moshe Ya’alon to investigate the issue when the fighting in the south ebbs.

Residents “have complained of hearing noises coming from under the ground. I have heard these complaints several times, but yesterday, when I came back from a tour of the Gaza border communities, I understood,” Malka wrote.

“If this is what they did in the south, I am certain [Hezbollah leader Hassan] Nasrallah is not sitting idly and giving out candy,” he said.

While the sandy and clay-like soil near Gaza is relatively easy to dig through, the boulder-strewn and rocky hills on Israel’s northern frontier are far harder to tunnel into. However, concerned ministry officials have turned to geologists at Tel Aviv University to investigate the potential subterranean threat.

“I can tell you that the issue of tunnels from Lebanon to Israel is really disturbing the security echelon,” one geologist said, adding that “There’s been a lot of talk about it and concerns.”

Acknowledging that “the defense establishment does not want to repeat the mistakes about tunnels in the Gaza Strip,” he noted that officials “want to find a quick solution and not get caught with their pants down,” another source close to the project said.

“Do not underestimate the possibility that Hezbollah dug a network of tunnels from the Lebanese border into Israel,” he stressed.

Not requiring reinforced ceilings against cave-ins, which have plagued the Gaza tunnelers is “an advantage,” said one, and added, “digging in the rocks is really more difficult: the excavation is slow, but there is no need to strengthen the tunnel roof, and it saves time on the job.”

He estimated that a several hundred meter cross-border tunnel could be dug within six months.

“It depends on the quantity of excavators and instruments they use to dig the tunnel,” he said.

“Since the Second Lebanon War, I believe that Hezbollah is investing a lot of money in this project. I know the exact amount, but I can’t tell you,” he added.

Additionally, a senior military official Channel 2 spoke with said that he believes Hezbollah and Hamas share valuable information on tunneling tactics and technology.

“There is a close connection between Hezbollah and Hamas, including transferring information on methods, strategy and of course the smuggling of weapons. I believe this is something that has been discussed in the army,” the source said.

“Hamas gave important information to Hezbollah on how to dig tunnels with all kinds of techniques and methods in light of the experience they have gained in recent years,” he said.

While the IDF found a tunnel opening and weapons caches just several hundred meters from northern communities in 2006, the tunnel didn’t reach Israel.

Deborah Danan contributed to this report.