A mountain roughly ten kilometres south of the Natanz nuclear complex has become the focal point of a new and more dangerous phase in the confrontation over the Islamic Republic's nuclear program. Known locally as Kolang Gaz La and more commonly in Western reporting as Pickaxe Mountain, the site appears to contain a large underground complex built behind four tunnel entrances, reinforced security zones, access roads, support areas, and extensive excavation works.
The project's declared origin was defensive. After an explosion and fire destroyed a surface facility used for assembling advanced centrifuges at Natanz in July 2020, senior nuclear officials announced that a larger, more modern replacement would be built inside a nearby mountain. Over the following years, commercial satellite images showed the construction expanding from site preparation into a substantial tunnelling operation. Piles of excavated rock grew on both sides of the mountain. Roads, perimeter barriers, patrol routes, fortified portals, and links to the wider Natanz security network followed.
What has never been publicly established is the full mission of the underground halls. The official explanation remains centrifuge production and assembly. Yet the estimated depth, scale, and configuration of the project have encouraged a wider set of assessments. The complex may be intended to store sensitive equipment, protect advanced centrifuge components, support uranium-related research, or provide space that could eventually be adapted for enrichment. Some assessments also raise the possibility of work involving highly enriched uranium metal or components relevant to a nuclear weapon. These remain scenarios rather than verified findings, but the uncertainty is itself strategically important.
Pickaxe Mountain matters because it may represent an attempt to solve the central vulnerability exposed by years of sabotage and military pressure: surface facilities can be infiltrated, burned, bombed, or disabled, while older underground sites may no longer be deep enough to guarantee survival. If the halls beneath the mountain are indeed buried under 80 to more than 100 metres of rock, the complex could be harder to destroy than Fordow, the previously dominant symbol of underground nuclear resilience.
That possibility has changed the language of deterrence. In July 2026, Donald Trump publicly named the site and said the United States was monitoring it continuously and would strike if activity justified action. His remarks elevated an obscure engineering project into a declared strategic target. Israeli analysis has likewise treated the mountain as a possible obstacle to any effort to dismantle the Islamic Republic's remaining nuclear capacity.
The result is a paradox. The deeper the complex is buried, the more valuable it becomes as protection against attack. But the more valuable it becomes, the more likely it is to attract the most aggressive forms of surveillance, sabotage, and military planning. Pickaxe Mountain is therefore not merely a bunker. It is a test of whether underground construction can preserve a nuclear program after conventional infrastructure has been repeatedly compromised, and whether the threat of overwhelming retaliation can compensate for the limits of even the most powerful bunker-busting weapons.
The project can be traced to the destruction of the above-ground centrifuge assembly centre at Natanz. In July 2020, an explosion and fire severely damaged the building. Officials of the Islamic Republic described the incident as sabotage, and it was widely attributed in the surrounding reporting to Israel. Whatever the precise method, the episode demonstrated that a critical part of the centrifuge supply chain remained exposed despite the heavy security surrounding Natanz.
The damaged building was not simply an industrial workshop. Advanced centrifuges are central to the speed and efficiency of uranium enrichment. A state that can manufacture, assemble, test, and replace these machines can recover more quickly from attacks on enrichment halls. Destroying an assembly centre therefore attacks the regenerative capacity of the program, not only its existing output. The decision to move the replacement facility into a mountain was a direct response to that vulnerability.
Ali Akbar Salehi, then head of the Atomic Energy Organization, publicly confirmed in September 2020 that construction had begun on a new underground hall in the mountains near Natanz. He described it as larger, more modern, and more comprehensive than the surface facility it would replace. This was significant because the project's existence was not initially revealed by a foreign intelligence service or opposition group. It was announced by the senior official responsible for the nuclear establishment.
Kazem Gharibabadi, then the Islamic Republic's representative to international organizations in Vienna, later reinforced the message that the destroyed facility would be replaced by a more advanced installation inside a mountain. He did not identify the exact location. Satellite analysis soon narrowed the search.
In October 2020, the Institute for Science and International Security reported signs of site preparation in mountainous terrain south of Natanz. At that stage, large-scale excavation was not yet fully visible. By late October, Rafael Grossi, director general of the International Atomic Energy Agency, confirmed that construction of an underground centrifuge assembly plant near Natanz had begun.
The subsequent development was incremental but difficult to conceal. Commercial satellite imagery revealed four principal tunnel entrances, two on the eastern side and two on the western side. Access routes were extended. Excavated spoil accumulated in quantities consistent with major underground works. Security rings widened around the mountain. The visible surface footprint did not reveal the internal architecture, but it made clear that the project was not a small shelter or a temporary storage area.
By early 2022, specialist assessments concluded that the underground halls were probably being placed deeper than those at Fordow. Later topographic calculations suggested that some sections might lie 80 to 100 metres below rock, with some estimates exceeding 100 metres depending on the alignment of the tunnels and the position of the main halls beneath the ridge. If the central chambers were constructed under the mountain's crest, individual access tunnels could extend for more than 300 metres.
The physical comparison with Fordow became unavoidable. Fordow has two known tunnel entrances and has long been treated as the model of a hardened nuclear facility. Pickaxe Mountain appears to have four. Fordow's protected areas have commonly been associated with an estimated depth of roughly 60 to 90 metres, while the new complex may sit deeper. The mountain itself also provides more terrain for concealed chambers, branching corridors, emergency routes, ventilation systems, utilities, and protected storage.
Construction did not end with excavation. In 2025, the Islamic Republic reportedly began building a double security perimeter with walls, fencing, and patrol roads around the mountain, connecting the protected zone to the broader Natanz complex. All four tunnel portals were cut between rock walls, which offered natural shielding and complicated direct observation. At least two entrances were strengthened with additional structures incorporating layers of concrete and earth.
After the later conflict, portions of the eastern approaches were reportedly filled with soil, restricting vehicle movement without completely sealing the tunnels. This could have served several purposes: limiting immediate access, concealing damage or activity, complicating targeting, or creating an easily reversible barrier. The incomplete closure suggests that the entrances retained operational value.
The chronology reveals a consistent pattern. Each external attack has pushed the nuclear infrastructure toward greater concealment and hardening. A damaged surface hall led to a mountain replacement. Repeated attacks on known facilities encouraged deeper construction. Public scrutiny of one site increased the value of redundancy elsewhere. The underground complex is therefore best understood not as an isolated project, but as the latest stage in an adaptive contest between offensive intelligence capabilities and defensive engineering.
The central intelligence problem is that visible construction does not reveal the contents of the mountain. Satellite imagery can show entrances, roads, spoil piles, power-related infrastructure, security boundaries, and changes in activity. It cannot by itself establish whether an underground hall contains machine tools, centrifuge components, enrichment cascades, uranium feed material, laboratories, or empty space reserved for future use.
The declared function is the production and assembly of advanced centrifuges. That explanation is plausible and strategically important on its own. A protected manufacturing and assembly centre would help the Islamic Republic replace centrifuges lost in sabotage or bombing and reduce the time required to restore enrichment capacity. It would preserve technical knowledge, specialized equipment, testing systems, and the industrial chain needed to maintain more advanced machines.
Yet the apparent scale of the excavation has raised questions about whether the project exceeds the requirements of assembly alone. One estimate cited a potential internal area of more than 500 square metres, while the network of tunnels and the volume of removed rock suggested room for multiple protected functions. Even if the initial mission is limited, underground halls can be repurposed. Storage rooms can become workshops. Workshops can be adapted for research. Empty chambers can later receive enrichment equipment if power, ventilation, cooling, and feed systems are installed.
Three possible missions dominate the analysis.
The first is a hardened centrifuge manufacturing and assembly complex. This is the most directly supported purpose because senior officials announced it after the 2020 sabotage. Such a facility would protect the industrial backbone of enrichment and make future attacks less decisive.
The second is a protected site for sensitive uranium-related work. This could include the handling, cooling, processing, or storage of material and equipment that the leadership considers too vulnerable to leave at known surface locations. Reporting described advanced industrial cooling equipment being transferred into hardened underground facilities from September 2025, although the exact destination and function were not independently established.
The third is a latent or active enrichment plant. The Institute for Science and International Security assessed that the estimated halls could be large enough to host enrichment operations in addition to centrifuge assembly. A site designed with sufficient electricity, cooling, ventilation, and cascade space could potentially be converted without requiring an entirely new excavation campaign. This would give the Islamic Republic a concealed reserve capacity at a time when Natanz and Fordow had been subjected to direct attack.
More speculative assessments extend the potential mission to activities involving highly enriched uranium metal and components relevant to an explosive device. Such claims require particular caution. Underground depth and secrecy may be consistent with highly sensitive work, but they do not prove that weaponization is taking place. The distinction between a facility capable of supporting a future weapons option and one actively manufacturing weapon components is fundamental, and the available evidence does not resolve it.
The strategic context, however, makes the ambiguity more consequential. The Islamic Republic had enriched uranium to 60 percent, a level substantially closer in technical terms to weapons-grade material than ordinary civilian reactor fuel. Senior figures increasingly spoke in public about the possibility that the state could reconsider its position on nuclear weapons, while diplomats continued to cite the supreme leader's religious decree against their production. The coexistence of these messages created deliberate uncertainty: formal denial remained intact, but the political cost of crossing the threshold was presented as conditional rather than unthinkable.
Assessments cited in the reporting suggested that the state could be roughly six months from producing a rudimentary nuclear explosive device under certain conditions. The later twelve-day war reportedly imposed severe constraints on that pathway by damaging enrichment, support, and military infrastructure. Yet the survival of Pickaxe Mountain meant that one potentially critical component of the system remained outside the confirmed destruction zone.
This is why the complex has strategic value even before its exact function is known. If it is operational, it may preserve capability. If it is incomplete, it may preserve a future option. If it is empty, it still forces adversaries to devote intelligence assets, military planning, and political attention to the possibility that it is not. Uncertainty becomes a form of deterrence because an attacker must plan against the most dangerous plausible use, while the defender can avoid revealing enough to confirm or disprove that assumption.
The site's proximity to Natanz further increases its significance. Natanz has been the main centre of the Islamic Republic's uranium enrichment infrastructure and has repeatedly faced sabotage, cyber operations, and military attack. A nearby mountain complex could share personnel, logistics, technical knowledge, and protected transport routes with the larger nuclear zone. It could also allow sensitive functions to be distributed between visible and concealed facilities, reducing the risk that a single strike would eliminate the whole system.
The complex may therefore serve as both shield and reserve. Its value lies not only in what is inside today, but in the range of activities it could support tomorrow.
Public discussion of Pickaxe Mountain has often moved between two exaggerated positions. One presents the complex as an impregnable fortress that no conventional weapon can destroy. The other assumes that any hardened facility can ultimately be neutralized if the United States and Israel apply enough force. Neither position fully accounts for the technical and operational problem.
Depth matters. A hall protected by more than 100 metres of rock may lie beyond the effective reach of weapons used against shallower targets, especially if the exact chamber location is uncertain. The GBU-57 Massive Ordnance Penetrator was associated in the reporting with the ability to strike depths relevant to Fordow. Pickaxe Mountain may exceed that envelope. Even a successful impact on the mountain does not guarantee that the explosive energy reaches the principal halls or destroys equipment distributed across separate chambers.
But survival is not the same as continued operation. A deeply buried installation depends on vulnerable systems that connect it to the surface. Electricity, ventilation, communications, cooling, drainage, access roads, portal structures, fuel supplies, emergency exits, and security infrastructure can all be attacked. A strike that fails to collapse the main chamber may still render the complex unusable for weeks or months. Conversely, sealing visible entrances may not destroy protected equipment or prevent eventual recovery if alternative routes exist.
The available analysis identifies three broad categories of attack.
The first is a coordinated air campaign. Israeli F-35 aircraft and American bombers could conduct successive waves against tunnel portals, ventilation points, electrical systems, roads, and support facilities. Heavy penetrator bombs would be used where geological and structural data suggested a chance of reaching buried spaces. Follow-on strikes would target repair crews, replacement power, reopened roads, and any exposed emergency access.
The logic of such a campaign would be cumulative rather than dependent on a single decisive impact. Initial strikes could isolate the site. Subsequent attacks could prevent restoration. Persistent satellite and drone surveillance would be used to identify movement, excavation, or renewed construction. The objective might not be to destroy every underground machine, but to deny safe access and stop the complex from performing its mission.
The limitation is uncertainty. Without accurate intelligence on hall locations, tunnel gradients, ventilation shafts, reinforced doors, and internal compartmentalization, even a large air campaign could produce ambiguous results. The deeper the facility, the harder it becomes to assess damage. Surface destruction can be photographed. Damage behind hundreds of metres of rock may remain unknown, allowing both sides to claim success.
The second category is a ground special operation. In the scenario described by security analysts, elite Israeli commandos, supported by American intelligence, logistics, electronic warfare, and air cover, could attempt to reach tunnel entrances or accessible internal sections. Small teams might place explosives on generators, control systems, tunnel junctions, or other critical infrastructure before withdrawing under cover of diversionary attacks.
Such an operation could be more precise than bombing if the teams reached the correct locations. It would also be extraordinarily risky. The mountain lies inside a heavily protected nuclear zone. The approaches are monitored, the terrain is difficult, and the defenders would have strong incentives to concentrate forces around the site during a crisis. Entry into a tunnel complex could expose commandos to blocked passages, ambush, and isolation. Extraction could be harder than infiltration.
A raid would therefore require a level of intelligence approaching internal knowledge: portal layouts, guard routines, blast doors, alarm systems, power distribution, escape routes, and the location of mission-critical equipment. Without that information, the operation could inflict symbolic damage while failing to neutralize the central capability.
The third category involves nontraditional methods. These include cyber operations intended to disable control networks, electronic attacks against communications and sensors, directed-energy or microwave systems aimed at vulnerable electronics, and small autonomous drones designed to enter tunnels. Attacks on cooling and ventilation could make certain spaces temporarily unusable even without collapsing them.
These options are attractive because they promise effects below the threshold of a full ground assault. They are also technically demanding and highly dependent on access. A cyber operation requires a pathway into isolated systems. Electromagnetic effects weaken with shielding and distance. Drones must navigate confined, defended tunnels and reach relevant equipment. None should be treated as a guaranteed substitute for physical penetration.
The strongest military conclusion is therefore narrower than claims of either invulnerability or easy destruction. Pickaxe Mountain may be extremely difficult to eliminate, but it is unlikely to be immune from disruption. Its entrances and support systems can be attacked. Its operations can be delayed. Personnel can be denied access. Reconstruction can be made costly. Yet permanent destruction of unknown halls beneath deep rock may remain beyond what can be confidently demonstrated from the air.
The debate over Fordow illustrates the danger of absolute language. For years, Fordow was described as too deep and too hardened to destroy. Later strikes challenged that confidence and were presented by their authors as devastating. Even then, the actual condition of the most deeply buried spaces was difficult to establish immediately. The lesson is not that every bunker can be effortlessly destroyed. It is that hardened sites have specific vulnerabilities, and those vulnerabilities may lie in systems surrounding the buried chamber rather than in the chamber itself.
Pickaxe Mountain was designed after the Islamic Republic had absorbed that lesson. Its engineers had the benefit of observing attacks on Natanz, the vulnerability of surface assembly halls, the scrutiny directed at Fordow, and the capabilities of modern surveillance. The complex is likely to reflect an effort to reduce known weaknesses. That makes old assumptions dangerous for both attacker and defender.
The public elevation of Pickaxe Mountain into a named target changed its political function. In July 2026, Trump said the United States had the site under surveillance and would act immediately if meaningful activity was detected. He emphasized the reach of American space-based observation and portrayed the level of activity as limited, while also threatening a severe strike if that changed.
The statement served several purposes. It warned the Islamic Republic that concealment had failed. It reassured supporters of the earlier campaign that the surviving complex had not been ignored. It also established a public trigger for future action, even though the threshold for "activity" remained undefined.
That ambiguity is dangerous. Construction, maintenance, vehicle movement, tunnel clearance, installation of equipment, or emergency repairs could all be interpreted differently by the two sides. One side may view such activity as routine preservation of infrastructure. The other may treat the same movement as evidence of nuclear reconstitution. When surveillance is constant and declared red lines are vague, misinterpretation can become a mechanism of escalation.
The Islamic Republic's response has also been framed in deterrent terms. A senior security official reportedly warned that an attack on the complex would bring a devastating response against American forces and Washington's regional allies. The warning undercuts the claim that the mountain is entirely immune from attack. A facility requiring explicit retaliatory protection is a facility whose loss is considered possible and strategically intolerable.
The threat also reveals how the complex fits into a wider system of protection. Physical depth is only one layer. The other layer is the prospect of regional retaliation through missiles, military forces, and allied networks. In this structure, the mountain does not need to be literally indestructible. It needs to be costly enough to attack that adversaries hesitate, or limited enough in its visible activity that they cannot easily justify escalation.
This is the logic of strategic ambiguity. The Islamic Republic can maintain that the facility is intended for peaceful centrifuge production while refusing to expose its full internal layout. It can invoke the religious prohibition on nuclear weapons while senior figures discuss circumstances in which policy might change. It can harden infrastructure as a defensive response to sabotage while creating spaces that could support rapid reconstitution or expansion.
The same ambiguity complicates international oversight. Inspectors can monitor declared facilities and material where access arrangements exist. They cannot verify every underground chamber merely because satellite imagery shows excavation. A mountain complex connected to a known nuclear zone can therefore occupy a grey area between declared industrial support and suspected undeclared capability. The absence of confirmed prohibited work does not resolve the suspicion, while suspicion alone does not prove a violation.
This uncertainty has consequences for the population as well as for military planners. A site embedded in a strategic nuclear landscape can turn surrounding communities, transport routes, utilities, and workers into part of a potential battlefield. Repeated sabotage and attack create risks of industrial accidents, displacement, and broader regional war. The deeper the confrontation becomes, the more civilian safety depends on decisions made inside institutions that disclose little and on foreign governments prepared to use force under conditions of incomplete information.
The history of the project also reflects a broader failure of accountability. The 2020 sabotage did not end advanced centrifuge work. It drove that work underground. Strikes on known sites did not eliminate the knowledge, personnel, and institutional commitment behind the program. They created incentives for dispersal, secrecy, redundancy, and harder targets. Each tactical success may therefore produce a new generation of infrastructure that is more difficult to inspect and more dangerous to attack.
This does not mean military pressure has had no effect. The reported twelve-day war damaged major facilities, disrupted timelines, and imposed severe constraints. It may have reduced the immediate capacity to produce a weapon. But the survival of Pickaxe Mountain illustrates the difference between damaging a program and ending it. Nuclear capability is not contained in a single building. It is distributed across expertise, machinery, material, command structures, procurement networks, and protected sites.
The central question is no longer simply whether a bomb can penetrate a mountain. It is whether repeated attacks can produce a stable political outcome when the targeted state responds by burying its most sensitive capabilities more deeply. If each strike generates a harder facility, and each harder facility generates a more ambitious attack plan, the confrontation becomes self-reinforcing.
Pickaxe Mountain is the physical expression of that cycle. It was born from sabotage, expanded under surveillance, hardened after repeated attacks, and transformed into a public target by presidential threat. Its actual contents remain uncertain, but its strategic meaning is already clear. It preserves the possibility that the Islamic Republic can rebuild elements of its nuclear infrastructure after devastating losses. At the same time, it gives the United States and Israel a new rationale for preventive action.
The most consequential feature of the site may therefore be neither its depth nor its machinery. It is the way it compresses technical uncertainty, political mistrust, and military escalation into one hidden space. A state convinced that only deeper concealment can protect its program faces adversaries convinced that concealment proves dangerous intent. Under those conditions, the mountain becomes more than a fortress. It becomes a mechanism through which the absence of verified knowledge can itself drive the next war.
