Israel's military has destroyed two Hezbollah tunnels beneath the Ali Al Taher ridge in southern Lebanon, using 1,100 tonnes of explosives, the Israeli army said.
Their destruction completes “the establishment of the security zone in southern Lebanon”, Israeli Prime Minister Benjamin Netanyahu's office announced on Thursday night.
The explosion caused a magnitude 4.1 tremor in the area, according to the US Geological Survey, with residents of Nabatieh describing a massive explosion throughout the region that left the ground shaking beneath their feet.
“I don’t know how to describe it. All the houses shook. It was like an earthquake. Windows were breaking,” Mahdi Salloum, a paramedic with the Nabatieh Ambulance Association, told The National by phone.
Before-and-after images shared by residents showed vegetation stripped from the ridge and significant changes to the shape of its crest.
“From the side where they [the military] entered, it has become like a desert,” Mr Salloum said. “Everything has been turned upside down, from the bottom to the top. And part of the top of the hill is gone as well.”
Seismic fears
The explosions happened very close to two significant seismic faults, said Marlène Brax, director of Lebanon's National Centre for Geophysics. “Both of these have generated historical earthquakes and remain active today,” she said.
The blasts added stress to an already active geological system, but it is impossible to say whether they posed an imminent earthquake risk, she said. "It is difficult to determine because we don’t know the state of equilibrium of the faults.”
Southern Lebanon is particularly affected by geological faults, and repeated explosions across the region have caused concerns among experts. “So far, fortunately, after all these explosions, including yesterday’s, there has been no change in seismic activity in the region," she said.
Trevor Ball, a weapons technical analyst at Armament Research Services, said the seismic activity could be explained by explosions detonated underground, which can generate stronger tremors than those detonated at the surface.
The Israeli army has increasingly used bulk explosives, he said, probably of a type similar to those used in commercial mining which are detonated in simple plastic jugs. The explosive material used in the attack would have cost around $1 million, he estimated.
The Israeli army said last week that it had cleared the area of Hezbollah fighters, some of whom were killed, while others fled.
Mohanad Hage Ali, deputy director for research at the Malcolm H Kerr Carnegie Middle East Centre, said the destruction of the Ali Al Taher tunnels completes the first phase of operations by Israeli forces in which they occupied a “buffer zone” in a 6km to 10km stretch of south Lebanon, demolished villages and infrastructure, and made the area uninhabitable.
The second phase, he said, is the establishment of 20 major Israeli positions or bases within the new security zone, which he said “will pave the way for a long-term occupation”.
Israeli media reported last week that the army plans to pull back to a 3km to 4km stretch of southern Lebanon which would serve as a defensive “buffer” between it and Hezbollah following the destruction of the tunnels. The National could not independently confirm the claim.
According to retired brigadier general Mounir Shehadeh, the destruction of Hezbollah’s tunnel infrastructure represents a “significant” and “painful blow”, but is not strategically “devastating” for the group as a military organisation.
The ridge was strategically important because its elevation provided Hezbollah with surveillance and fire control capabilities over the surrounding area. “The underground infrastructure allowed Hezbollah to maintain its combat capabilities despite Israel’s air superiority,” Mr Shehadeh said.
Ali Al Taher ridge is also a key location linking the Bekaa Valley and southern Lebanon – a crucial route in Hezbollah’s logistical network.
Israel said the underground complex extended for over 2 kilometres and served as a Hezbollah command centre, with weapons depots containing missiles, drones, anti-tank weapons and explosives.
A joint statement by Mr Netanyahu and Israeli Defence Minister Israel Katz said the ridge contained “strategic terrorist infrastructure that was built over two decades, with Iranian funding and planning”.
“The terror infrastructure and the command centre on the ridge were designed to serve as the staging base for the conquest of the Galilee, and had observation and fire dominance over Metula and Kiryat Shmona,” Mr Netanyahu and Mr Katz said.
They said Israeli forces would continue to occupy southern Lebanon in the “security zone”.
They added that its destruction “completes the achievement of operational control over Ali Al Taher ridge – above and below ground”.
What comes next?
Multiple scenarios for the next phases are possible. Control of Ali Al Taher provides Israel with operational depth north of the area it occupies in southern Lebanon, including towards the city of Nabatieh, which has come under heavy Israeli bombardment in recent days.
While Mr Shehadeh does not expect the Israeli army in the short term to advance towards Nabatieh, a move that could trigger complex urban warfare, control of Ali Al Taher offers Israel immediate strategic gains as part of its broader effort to reshape its deployment in southern Lebanon, he said.
“I therefore believe the most likely scenario in the next phase is not a direct advance on Nabatieh, but an expansion of control over the elevated positions and routes surrounding it, while using air power, artillery and drones to impose a deeper buffer zone.”
This aligns with reports of a transition to the so-called “grey line”, he argued, under which the Israeli army would reduce the depth of its presence inside Lebanese territory to between three and four kilometres.
Controlling strategic high ground and establishing permanent military positions there would allow the Israeli army to withdraw some of its ground forces.
For now, the Israeli army has withdrawn from the Ali Al Taher ridge and repositioned its forces along rear lines in the Beaufort area, according to Israeli Army Radio. It said Israeli forces would maintain fire control over the ridge and confront any attempt by Hezbollah to return.
The second scenario involves potential Iranian retaliation. Iran last month warned that it would respond forcefully to any attack on Hezbollah's positions on the ridge. Iran appears to be gaining ground in the broader regional conflict between it and the US, with its Yemeni proxy, the Houthis, claiming control of the Bab Al Mandeb strait on Thursday.
Mr Hage Ali of Carnegie sees potential for “regional escalation that's taking place from Iran to Yemen, and soon probably Lebanon and Iraq”.
“It makes sense … that we might see an escalation on that front and Iran would respond using all of its cards, including Hezbollah,” he said.
Israeli control of the Ali Taher ridge would place its forces at a strategic advantage in such an event, leaving them capable of potentially capturing Nabatieh – the largest town in south Lebanon's eastern sector.
