Trump has threatened to strike Iran's heavily fortified Pickaxe Mountain nuclear complex near Natanz
The underground tunnel network could house advanced centrifuges and future uranium enrichment activities
The IAEA warns attacks on nuclear facilities risk severe radiological and environmental consequences
US President Donald Trump has publicly threatened to target a sprawling underground Iranian nuclear facility known as "Pickaxe Mountain," in a statement made on social media platform The Truth Social. Pickaxe Mountain is a vast tunnel complex south of the Natanz enrichment plant that remains under construction and has not yet been struck in either the 2025 or 2026 wars.
The mountain, known locally as Kuh-e Kolang Gaz La, houses a tunnel complex constructed in the fall of 2020. Iran announced at the time that the underground halls were intended to replace the destroyed above-ground advanced centrifuge assembly facility at the main Natanz site, which was capable of assembling about 6,000 advanced centrifuges per year, according to Institute for Science and International Security (ISIS).
Location And Scale Of The Facility
The tunnel complex is part of a large secured perimeter that includes another, smaller tunnel complex initially built in 2007, which was expanded and hardened in recent years and sealed shortly after the June 2025 war, as per ISIS.
The Pickaxe Mountain facility features two pairs of entrances leading under the ridge of the mountain. They are assumed to lead to one facility, though this is not guaranteed. The facility is estimated to be at least 100 metres deep under the mountain. The mountain has a height of 1,608 metres above sea level, with the difference in elevation between the eastern entrance and the mountain ridge about 145 metres, and about 100 metres for the western entrance. The difference in elevation between the two sets of entrances of about 50 metres could indicate that the facility has multiple levels, according to ISIS.
The physical defensive measures consist primarily of a large security perimeter and extensive tunnel entrance hardening. In 2025, Iran started constructing a double (fence and wall) security perimeter with a patrol route surrounding the entire mountain and adjoining the Natanz Nuclear Complex security perimeter.
All four tunnel entrances are excavated in a channel of rock. Two of the four tunnel portals feature entrance extensions with subsequent hardening, including layers of concrete and earth. Since the wars, Iran partially backfilled the pair of eastern tunnel portal entrances to obstruct ground vehicle access but did not seal them fully, as previously noted at the 2007 tunnel, the Esfahan tunnel, or the Fordow underground enrichment plant, ISIS reported.
Purpose and Vulnerabilities
It remains unclear when Pickaxe Mountain could become operational based solely on assessments of satellite imagery. It is also unclear if Iran still plans on installing a large-scale assembly facility, given the destruction of Iran's centrifuge program, including Iran's ability to make centrifuge components needed for an assembly plant.
However, the space available under the mountain could be expected to be large enough to also hold a centrifuge enrichment plant capable of producing weapon-grade uranium. It is likely large enough to also hold certain nuclear weaponisation activities such as making weapon-grade uranium metal and shaping it into nuclear weapon components, ISIS noted.
As per the report, any operations inevitably have ties to the outside, including via imported equipment, power supply, ventilation, heating, cooling, construction personnel, operating personnel, and deliveries. All of these connections to the outside present vulnerabilities that the US and Israel would seem to be able to exploit.
The site, in its present condition, would be more suitable for ground forces to attack or sabotage, like the destruction of the advanced centrifuge assembly center, which reportedly involved explosives brought into the facility during its construction. However, vulnerabilities may also exist that can be exploited by deep earth penetrating weapons via aerial attacks.
IAEA Warnings On Nuclear Sites
The International Atomic Energy Agency (IAEA) has repeatedly warned against attacks on nuclear facilities. In June 2025, IAEA Director General Rafael Grossi told the UN Security Council that "attacks on nuclear sites in the Islamic Republic of Iran have caused a sharp degradation in nuclear safety and security in Iran. Though they have not so far led to a radiological release affecting the public, there is a danger this could occur."
Grossi warned specifically about the Bushehr Nuclear Power Plant, stating: "In case of an attack on the Bushehr Nuclear Power Plant a direct hit could result in a very high release of radioactivity to the environment. Similarly, a hit that disabled the only two lines supplying electrical power to the plant could cause its reactor's core to melt, which could result in a high release of radioactivity to the environment."
Following the June 2025 strikes, Grossi noted that the Natanz enrichment site had suffered significant damage, with the above-ground part of the Pilot Fuel Enrichment Plant "functionally destroyed" and strikes on the underground cascade halls "seriously damaging." He said there was both radiological and chemical contamination inside the facility, with the main concern being chemical toxicity of Uranium Hexafluoride and Fluoride compounds.
The IAEA has stressed that while off-site radiation levels remain normal, any attack on an operational nuclear facility could necessitate protective actions such as evacuations and sheltering of the population, with the reach extending to distances from a few to several hundred kilometres.
