Beneath the Fortress: Inside the IDF's Exposure of Hezbollah's Subterranean War Machine — and the Cost of Destroying It

On June 7, 2026, the Israel Defense Forces released footage of a sprawling tunnel complex discovered beneath the ridgeline near Beaufort Castle in south Lebanon — a medieval Crusader fortress that has changed hands repeatedly across centuries of conflict. The IDF described the site as a "significant command-and-control center, where hundreds of Hezbollah operatives were stationed" and said it had been constructed with "direct Iranian assistance" [1]. Troops from the Golani Brigade, Maglan Commandos, and Yahalom Combat Engineers were still mapping the full extent of the network as of publication [1].

Days earlier, the IDF had announced the killing of Abed Harb, Hezbollah's chief explosives engineer and commander of its engineering unit, in an airstrike. Harb had been responsible for "numerous attacks against IDF soldiers" over two decades, and his death was described by analysts as a loss of irreplaceable institutional knowledge for the organization [2][3].

Together, these disclosures form the latest chapter in a conflict that has killed thousands, displaced over a million people, and raised fundamental questions about the limits of military force, the meaning of sovereignty, and the durability of underground warfare.

The Scale of the Underground Network

Hezbollah's tunnel system in south Lebanon is not a recent improvisation. Researchers at the Alma Research and Education Center assessed a potential 45-kilometer attack tunnel route in south Lebanon as early as 2022, and the cumulative network spans "hundreds of kilometers," connecting positions south of the Litani River to strongholds in the Beqaa Valley and Beirut [4][5].

The tunnels differ fundamentally from the Hamas tunnel network in Gaza. Where Hamas dug through sandy soil with hand tools, Hezbollah's tunnels are carved through solid rock using industrial drills — a process that takes months or years per segment but produces structures of exceptional durability [5]. Some reach depths exceeding 100 meters. The Beaufort complex, located approximately one kilometer south of the castle and six kilometers from the Israeli town of Metula, featured water and electricity infrastructure, anti-tank and anti-aircraft capabilities, living quarters, showers, an operating room, and kitchens [1].

In April 2026, the IDF destroyed two additional tunnels totaling approximately two kilometers in length, situated about 10 kilometers from Israel's northern border, which it said were built over a decade with "direct guidance" from Iran and reached depths of 25 meters [6]. Near Kantara, troops dismantled what the military described as the "largest Hezbollah tunnel city in all of southern Lebanon" [7].

Source: IDF/Alma Research Center

Data as of Jun 8, 2026CSV

The pace of discoveries has accelerated sharply since the 2026 ground campaign began. During Operation Northern Shield in 2018, the IDF identified six cross-border attack tunnels. By contrast, dozens of tunnel sites and underground facilities have been uncovered since the 2024 ground incursion resumed [5][6].

The Bomb Network: What Was Found

Separate from the tunnel infrastructure, the IDF exposed what it described as a covert explosives manufacturing and distribution network. Footage showed troops dismantling a booby-trapped warehouse containing containers filled with nails and sharp metal objects — components of anti-personnel shrapnel devices — alongside propane tanks that could be used against armored vehicles or structures [2].

Nick Reese, a former senior intelligence official cited in reporting on the discovery, characterized the site as "a central general-purpose explosives-making facility" and noted: "The method is not particularly sophisticated but shows that they were targeting humans, not simply hardware or infrastructure" [2].

IDF soldiers have been killed by Hezbollah-planted IEDs during the current campaign. Sgt. First Class (res.) Lidor Porat died when his engineering vehicle drove over a buried bomb, and Warrant Officer (res.) Barak Kalfon was killed in a separate IED explosion [8]. Anti-tank missiles and explosive-laden drones have wounded additional soldiers, including a brigade commander severely injured on May 20, 2026 [8].

The Iranian Supply Chain

The tunnel and bomb infrastructure has a documented foreign supply chain. Iran's Islamic Revolutionary Guard Corps (IRGC), through its Quds Force, supplied Hezbollah with approximately 670 tons of ammonium nitrate in 2013 and 2014, at a cost of roughly $72,000 per shipment [9]. German newspaper Die Welt and Israeli intelligence reports detailed at least four deliveries: 270 tons in July 2013, another 270 tons in October 2013, and two further shipments in 2014 [9][10].

The logistics involved Iranian front companies. Liner Transport Kish (LTK), managed by Shahriyari and Mojtaba Mousavi Tabar, handled maritime deliveries, while at least one air shipment traveled via Mahan Air, an Iranian carrier widely assessed as a Revolutionary Guard front [9]. On Hezbollah's end, Mohammad Qasir — the group's logistics chief for two decades — oversaw payment and receipt [9].

The ammonium nitrate was not confined to Lebanon. The U.S. State Department warned in 2020 that Hezbollah had been transporting ammonium nitrate across Europe since 2012, concealed in first-aid cold packs, with supplies identified in the United Kingdom, Germany, and Cyprus [10]. Iran and North Korea also provided technical expertise for tunnel construction, according to the West Point Modern War Institute [5].

Civilian Toll: The Numbers on Both Sides

The military campaign to destroy this infrastructure has carried an asymmetric human cost.

On the Israeli side, 23 soldiers and one civilian contractor have been killed since hostilities resumed in 2026 [8]. Hezbollah rocket attacks have killed at least two people in Israel during the same period [11].

On the Lebanese side, the toll is orders of magnitude larger. The Lebanese Health Ministry reported almost 3,200 people killed and nearly 10,000 injured in the renewed Israeli campaign through late May 2026 [8]. During the post-ceasefire period between November 2024 and February 2026, the UN Human Rights Office documented at least 127 civilian deaths from Israeli strikes in southern Lebanon [12].

Source: Lebanese Health Ministry / HRW / OHCHR

Data as of Jun 8, 2026CSV

The April 8, 2026 strikes alone — which hit over 100 targets across Lebanon, including densely populated Beirut neighborhoods — killed more than 300 people and injured over 1,150 in a single day [11]. The strikes destroyed or severely damaged nine bridges over the Litani River, isolating approximately 150,000 people in areas south of the river [11]. Six hospitals were forced to close, and markets and pharmacies in the affected zone largely shut down [11].

Amnesty International documented the destruction of 10,803 structures across 26 border municipalities between October 2024 and January 2025 alone. In three villages — Yarin, Dhayra, and Boustane — more than 70% of buildings were destroyed [13]. Agricultural assets in Nabatieh district suffered 58% destruction [13]. Some demolitions occurred after the November 2024 ceasefire and "outside the context of active combat," Amnesty concluded, raising questions about military necessity [13].

Over one million Lebanese — more than 20% of the country's population — have been displaced since the conflict began [8].

The Legal Debate: Proportionality and Sovereignty

The IDF has framed the tunnel sites as legitimate military targets under international humanitarian law (IHL), arguing that they constitute active command-and-control infrastructure from which attacks on Israeli territory are planned and executed [1]. Under the principle of distinction in IHL, military objectives — including underground bunkers used for combat operations — are lawful targets if the anticipated military advantage of their destruction is not outweighed by expected civilian harm.

Legal scholars and international organizations have challenged whether that standard has been met.

Human Rights Watch argued that even if the bridges and tunnel sites qualify as military objectives, "disproportionate attacks include those expected to cause excessive civilian damage relative to anticipated military advantage" and may constitute war crimes [11]. Amnesty International found evidence of systematic destruction that appeared to lack "imperative military necessity," including the bulldozing of civilian homes, mosques, parks, and a soccer field in Kfar Kila while the Israeli military maintained full control of the area [13].

Mireille Rebeiz, a legal scholar who studies Hezbollah's status under international law, has emphasized that "the presence of a Hezbollah commander, rocket launcher, or any military installation within a civilian area does not warrant an attack on that area without consideration for the civilian population" [14]. The principle of proportionality remains binding on Israel regardless of whether Hezbollah has unlawfully placed military assets in civilian zones [14].

The sovereignty question cuts deeper. Israel's operations inside Lebanon — including the seizure of Beaufort Castle and extended military presence south of the Litani — constitute actions on the territory of a sovereign state. UN experts warned in October 2025 against "continued violations of ceasefire in Lebanon," urging protection of civilians [12]. The UN Security Council's August 2025 adoption of Resolution 2790, which extended UNIFIL's mandate for a final time through December 2026 while ordering a full drawdown, signaled diminishing international appetite for maintaining the peacekeeping status quo [15].

Hezbollah's Rationale and Domestic Legitimacy

Hezbollah has long framed its military infrastructure — including the tunnel network — as defensive resistance against Israeli occupation of the Shebaa Farms, a disputed 25-square-kilometer strip of land on the Lebanese-Syrian-Israeli border [16]. After Israel's withdrawal from south Lebanon in 2000, Hezbollah retained the Shebaa Farms dispute as the primary justification for maintaining an independent armed force outside the control of the Lebanese state [16].

The argument carries genuine domestic resonance for segments of Lebanese society, particularly within Shia communities and some allied political factions. But independent Lebanese analysts have long identified the Shebaa framing as a strategic pretext. The National reported that Hezbollah "made a strategic decision to keep its arms and continue the armed struggle against Israel" after the 2000 withdrawal, and "needed a pretext" — one the Shebaa Farms conveniently provided [16].

Hezbollah also invokes serial Israeli violations of Lebanese airspace and territorial sovereignty, which are documented and ongoing, as additional justification [16]. The group's supporters argue that in the absence of a capable Lebanese military deterrent, its tunnel and weapons infrastructure constitutes the only realistic defense against Israeli aggression.

Critics counter that the infrastructure serves primarily offensive purposes — cross-border attack tunnels are not defensive — and that Hezbollah's parallel state apparatus undermines the very sovereignty it claims to defend.

The Lebanese State's Knowledge Problem

A central unanswered question is what the Lebanese Armed Forces (LAF) and the Lebanese government knew about the tunnel network's location and extent.

The Foundation for Defense of Democracies reported in March 2026 that the LAF under commander Rodolphe Haykal had effectively "defied the state it is sworn to serve," with military statements echoing "Hezbollah's rhetoric far more than the government's directive" [17]. The LAF has been criticized for cooperating with Hezbollah in clearing evidence of UN Resolution 1701 violations before UNIFIL inspections [17].

This dynamic — whether characterized as complicity, coercion, or institutional incapacity — exposes what scholars describe as "hybrid sovereignty" in Lebanon, where state and non-state security actors produce "negotiated sovereignty rather than simple state weakness" [14]. The LAF's annual budget is a fraction of Hezbollah's estimated military expenditure, and the state's intelligence apparatus lacks the capacity — or political mandate — to independently monitor Hezbollah's construction activities across the south.

UNIFIL's effectiveness has been similarly constrained. Resolution 1701, adopted after the 2006 war, called for Hezbollah's disarmament and the exclusion of all armed forces except UNIFIL and the LAF south of the Litani. Nearly two decades later, "virtually all of southern Lebanon is a Hezbollah maze of underground bunkers, rocket-launch sites and interconnecting tunnels," as AIPAC documented in a 2019 assessment [18].

Can the Network Be Permanently Destroyed?

The Hamas precedent is instructive. After Israel's 2014 Operation Protective Edge, which destroyed 32 tunnels in Gaza, Hamas rebuilt and expanded the network within three years, eventually constructing "hundreds of kilometers" of new tunnels [19]. Following the 2021 Operation Guardian of the Walls, Hamas leadership authorized $225,000 specifically to install blast doors against future bunker-buster strikes [19]. The estimated total investment in the Gaza tunnel network exceeds $1 billion [19].

Hezbollah's tunnels present a harder engineering challenge for reconstruction — the rocky terrain that makes them durable also makes them expensive and slow to rebuild. But Hezbollah has demonstrated the organizational capacity and Iranian financial backing to sustain multi-decade construction programs. The group has been fortifying positions in south Lebanon since 2008 using large quantities of construction materials [4].

The IDF's 98th Division, which trained extensively in Gaza tunnel warfare before deploying to Lebanon, has applied underground combat techniques developed against Hamas [5]. But military officials have not publicly claimed the capacity to permanently degrade Hezbollah's tunnel-building capability. The destruction of the Beaufort complex and the Kantara site represents tactical success, but strategic permanence depends on variables — sustained Israeli military presence, effective Lebanese state control, international monitoring — that remain unresolved.

The UNIFIL drawdown ordered for 2026, combined with the LAF's demonstrated unwillingness or inability to confront Hezbollah's infrastructure program, suggests the conditions for reconstruction will persist once Israeli forces withdraw.

What Comes Next

The exposure of the Beaufort tunnel complex and the bomb network marks a significant intelligence and military achievement for the IDF. It has provided concrete visual evidence of what analysts long suspected: that Hezbollah built a subterranean military infrastructure of a scale and sophistication that rivals or exceeds anything constructed by non-state actors in modern warfare.

But exposure is not the same as resolution. The human cost — thousands of Lebanese civilians killed, over a million displaced, entire communities leveled — has generated international legal scrutiny that extends well beyond the tunnels themselves. The asymmetry in casualties, the destruction of civilian infrastructure far from any tunnel site, and the continued military operations in a sovereign nation whose own armed forces cannot or will not assert control over its territory: these are the unresolved tensions that will define what follows.

The tunnels can be demolished. The question is whether anything will prevent new ones from being dug.