This week began with strenuous Israeli military activity all along the border fence with the Gaza Strip, including a troop buildup, Merkava Mark 4 tanks’ deployment and preparation of temporary congregation and parking lots. The IDF also closed off roads to civilian traffic and instructed farm workers to stay away from the fields along the border. Clearly, something was afoot below ground, even as tense calm prevailed above. On Oct. 20, the secret was revealed with an IDF announcement that it had identified a Hamas attack tunnel dug from Gaza stretching a few dozen of meters into Israel. “A very, very significant terror tunnel,” was how IDF Chief Lt. Gen. Aviv Kochavi described it the next day.

The tunnel is not only significant and strategic in nature, it is also the first known dividend of the massive underground barrier that Israel has dug along the Gaza border to a depth of several dozen meters. The “barrier,” as it is dubbed, is a unique and highly complex Israeli innovation designed to put an end to the strategic tunnel weapon developed and used by Hamas in recent years when it realized it would be unable to prevail against the IDF on the ground, in the air or sea. With the recent quasi-completion of the barrier, Hamas has also been deprived of this subterranean military theater.

The new tunnel was discovered by the sophisticated sensor technology mounted on the barrier deep below ground. The wall — at the cost of hundreds of millions of dollars — is equipped with technology to detect movement, drilling and any type of work conducted below ground. The tunnel appears to have been detected on Oct. 18. The next day, powerful drilling equipment was brought in and found the tunnel that had crossed the borderline and came very close to the barrier constructed on the Israeli side. “The most significant tunnel we have seen to date, both in terms of depth and infrastructure,” a senior Israeli military source told Al-Monitor on condition of anonymity.

The IDF has declined to reveal further details, but Hamas is believed to have invested heavily in a deeper and wider tunnel than those it had dug before, equipping it with electricity, phone lines and other means that turned it into a strategic weapon of particularly lethal potential ready to send terrorists into Israel to mount attacks and kidnappings. Hamas employed dozens of laborers working in shifts 24/7 in great secrecy to dig the tunnel. “The damage to Hamas from exposure of this tunnel is substantial,” a senior Israeli security source who spoke on condition of anonymity told Al-Monitor. “Money, energy, work and time that could have been invested in caring for the impoverished residents of Gaza.”