May 2026 — New commercial satellite images show heightened activity and fortification efforts at a secretive underground tunnel complex in Iran, raising fresh concerns about the country’s nuclear program amid ongoing regional tensions.
Analysts at the Institute for Science and International Security (ISIS), a Washington-based nonproliferation research group, have identified significant changes at the Mount Pickaxe facility — also known as Kūh-e Kolang Gaz Lā or Pickaxe Mountain. The site is located just south of Iran’s Natanz nuclear enrichment complex and has never been inspected by the International Atomic Energy Agency (IAEA).
According to images from Airbus Defence and Space analyzed by ISIS:
- As of April 22, 2026, the two eastern tunnel entrances were blocked with special soil or material. This change was still visible in imagery dated May 2.
- On April 1, the same entrances were open.
- No similar blocking had yet been observed at the western entrances.
- The material used would require heavy equipment to remove, effectively obstructing rapid vehicle access while not fully concealing the portals.
These developments follow earlier construction work at the site, including concrete reinforcement of older tunnel entrances earlier in 2026. Experts believe the activity could be aimed at protecting or concealing valuable equipment, materials, or assets stored deep underground.
A Deeply Buried Fortified Complex
Construction of the Pickaxe Mountain facility reportedly began around 2020, possibly to house a modern centrifuge assembly hall following sabotage incidents at the nearby Natanz site. The complex features multiple sets of tunnel portals on the eastern, western, and southern sides. Work has accelerated since U.S. and Israeli strikes on Iranian nuclear-related targets in mid-2025, with the addition of perimeter security walls and other hardening measures.
The site’s deeply buried nature makes it difficult to monitor and potentially resistant to conventional airstrikes. Analysts suggest possible functions include advanced centrifuge production, metallurgy work, or even clandestine uranium enrichment activities, though its exact purpose remains unverified without direct inspections.
Broader Pattern of Fortification
The activity at Pickaxe Mountain fits into a larger pattern of Iran reinforcing its nuclear and military infrastructure. In recent months, satellite imagery has shown repairs, new roofing over damaged structures, and the use of soil and concrete coverings at other sensitive sites, including areas near Isfahan and Natanz.
Iran has consistently limited international oversight of its nuclear program, further fueling suspicions. The combination of underground expansion, rapid fortification, and lack of transparency continues to worry nonproliferation experts and Western governments.
While commercial satellite imagery provides valuable open-source insights, only on-site access by IAEA inspectors could clarify the true nature of activities at facilities like Pickaxe Mountain. As tensions persist, such sites are likely to remain under close scrutiny from intelligence agencies and research organizations worldwide.
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