US President Donald Trump has threatened fresh strikes on Iran's nuclear facilities as tensions between Washington and Tehran continue to escalate. Among the sites under scrutiny is the Pickaxe Mountain area, a heavily fortified underground facility.
According to a Wall Street Journal report, Israel shared intelligence with the US indicating that Iran relocated uranium-enrichment centrifuges to the Pickaxe Mountain site last autumn.
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Israeli intelligence believes the centrifuges, which are used to enrich uranium, are a key step in producing nuclear fuel and, potentially, nuclear weapons, were transferred to the underground complex.
Located south of the Natanz uranium enrichment complex, Pickaxe Mountain is an underground nuclear-related facility. Natanz, which houses two uranium enrichment plants, has been struck several times, including during the conflict that began on Feb. 28 this year and the 12-day war in 2025.
The facility is located within a heavily secured perimeter that also houses a smaller tunnel complex built in 2007. The older complex was expanded and reinforced in recent years before its entrances were sealed shortly after the June 2025 conflict.
According to the Institute for Science and International Security, a US-based think tank that has analysed satellite imagery of the site, construction of the Pickaxe Mountain facility began in 2020 after an explosion at the Natanz nuclear complex. Iranian authorities had attributed the blast to an act of sabotage.
At the time, Iran said the underground halls were being built to replace the advanced centrifuge assembly facility at Natanz that had been destroyed in the explosion.
The above-ground plant was capable of assembling about 6,000 advanced centrifuges annually. It was intended to support a significant expansion in centrifuge production as restrictions under the Joint Comprehensive Plan of Action (JCPOA) were scheduled to be phased out between 2025 and 2030.
What Has Iran Built Inside Pickaxe Mountain?
According to the Institute for Science and International Security, the Pickaxe Mountain site has two pairs of tunnel entrances that are believed to provide access to a single underground complex. However, the think tank said this assessment cannot be confirmed with certainty.
The facility is estimated to be buried at least 100 metres beneath the mountain, which rises 1,608 metres above sea level.
The eastern tunnel entrance is located about 145 metres below the mountain ridge, while the western entrance is roughly 100 metres below it.
The nearly 50-metre difference in elevation between the two entrances has led analysts to believe the complex may span multiple underground levels, according to a report by Business Standard.
According to a Reuters report, reinforcing the tunnel entrances would make it significantly more difficult to strike the facility using deep-penetrating weapons, including bunker-buster bombs designed to destroy underground targets.
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