Israel’s campaign to neutralize Hamas’s subterranean infrastructure has become a laboratory for modern counter‑subterranean warfare. What began as targeted strikes on command nodes and cross‑border smuggling shafts evolved into a wider effort to deny Hamas the tactical advantages of integrated tunnel systems. The methods fielded against those networks have ranged from conventional engineering to specialized ordnance designed to collapse or render tunnels unusable. The operational choices made in 2023 and 2024 continue to shape both the immediate battlefield and the long term politics of Gaza.

At the center of the controversy are so called tunnel‑buster or bunker‑busting munitions. These are large warheads and designed fuses intended to penetrate soil, concrete and buried infrastructure before detonating. In several high profile strikes analysts identified or concluded that 2,000 pound class munitions and JDAM guidance kits were used against dense Gaza neighbourhoods, producing large, deep craters consistent with delayed detonation on penetration and with the aim of destroying subsurface facilities. Such weapons can achieve the military goal of collapsing tunnels or destroying hardened chambers, but they do so at a physical scale that risks catastrophic aboveground damage when used in densely populated urban areas.

The United States role in enabling this capability is consequential. Reporting in late 2023 documented transfers of US bunker‑busting warheads and large numbers of heavy conventional bombs to Israel. Those transfers mattered because JDAM kits and 2,000 pound class warheads are the ordnance most effective at defeating deep or heavily reinforced subterranean structures. The speed and volume of transfers during the conflict also narrowed policy options for allies who might have preferred smaller, lower‑yield munitions be prioritized in urban operations.

Operationally, air‑delivered bunker busters were only one tool. Ground engineers and field units used a portfolio approach: mechanical collapse with armored bulldozers, controlled explosive charges tailored to soil and tunnel construction, injection of cement‑like sealants and rapidly expanding foams to block passages, and in some reported instances attempts to flood tunnel sections. Each method has trade offs. Bulldozers can close entrances and deny access without indiscriminate blast effects but they expose crews and require secure areas to operate. Flooding can be impractical in porous soils and is difficult to scale. Injected foams and sealants offer a lower‑signature option but can be circumvented or require repeated application. The mix of techniques reflects the complexity of Gaza’s tunnel environment and the operational imperative to limit casualties among assaulting forces.

Beyond technical effectiveness, a distinct set of humanitarian and legal issues has emerged. Independent investigations and visual munitions analysis tied heavy JDAM‑equipped strikes to large civilian harm in crowded neighbourhoods. Human rights organisations documented remnants of US‑made guidance kits on strike sites and called for investigations into whether strikes complied with the principles of distinction and proportionality under international humanitarian law. Separate reporting has alleged that the byproducts of deep penetration strikes can produce lethal concentrations of carbon monoxide or other asphyxiating gases in enclosed subterranean spaces, effectively turning a struck tunnel into a confinement chamber for anyone inside. Those claims, if substantiated, raise additional legal and moral questions about the foreseeable effects of particular munitions in underground settings.

Strategically the use of tunnel‑targeted heavy ordnance reshapes the post‑conflict landscape. Physically collapsing tunnels under urban blocks contributes to wide swathes of structural collapse and rubble fields that will complicate reconstruction for years. The destruction of belowground utility corridors and the compaction of urban debris raise the cost of rebuilding and increase the humanitarian burden on donors and neighbours. Politically, the visible use of oversized munitions in civilian areas amplifies international scrutiny and isolates partners who are seen as enabling such campaigns. It also creates an incentive for armed groups to invest in deeper, more distributed and harder to detect subterranean networks in any future contest, accelerating a subterranean arms race that will drive demand for both counter‑tunnel tools and improvised deception techniques.

From a policy perspective there are three intersections that deserve urgent attention. First, arms export and end‑use controls must be tightened when weapons calibrated for deep penetration are transferred into dense urban contexts. Rapid emergency transfers without commensurate transparency and safeguards narrow political options and undercut attempts to manage civilian risk. Second, independent, timely investigations into specific strikes and reported after‑effects — including allegations of lethal gas accumulation in tunnels — are necessary to establish facts, assign responsibility where warranted and restore a modicum of accountability. Third, stabilization planning must treat subsurface remediation as a core reconstruction task. Clearing collapsed tunnels, mapping residual underground hazards, and remediating contaminated voids will require specialized engineering teams and sustained funding beyond conventional rubble removal.

The tactical problem Hamas posed with its extensive subterranean network demanded countermeasures. The strategic problem now is that those countermeasures produce legacies that will complicate peace, recovery and regional politics for years. If the international community cares about reducing future cycles of violence it must not treat counter‑subterranean capability as a purely technical fix. Instead policy makers should pair any legitimate military need to defeat underground threats with stricter export oversight, independent inquiry into wartime conduct, and long term commitments to urban and subsurface reconstruction. Failure to do so will leave Gaza physically and politically less stable, accelerate underground containment strategies by non‑state actors elsewhere, and normalize the deployment of high‑yield, deep‑penetration weapons in circumstances where the costs to civilians and recovery are unacceptably high.