Israeli intelligence believes Iran moved thousands of uranium-enrichment centrifuges into tunnels deep inside a mountain last fall, Israeli and US officials say, a development that would heighten concerns that Tehran could reconstitute its nuclear program.
According to The Wall Street Journal, Israel passed along the intelligence findings to the US, saying the centrifuges were transferred to the Pickaxe Mountain site last fall after the 12-day war in June when American and Israeli strikes pummeled Iran’s three main nuclear sites.
The presence of centrifuges at Pickaxe Mountain does not necessarily mean that Iran is establishing an enrichment facility there. Following the June 2025 bombings, Tehran may have moved surviving centrifuges to the site to reduce the risk that they would be destroyed.
Known in Iran as Mount Kolang, the site has been under US and Israeli surveillance for years. Pickaxe Mountain is located about 2 kilometers south of Iran's Natanz nuclear facility, which was struck during the latest round of US military operations that began February 28.
The International Atomic Energy Agency has said the above-ground enrichment facility in Natanz was destroyed. The other, underground enrichment facility was likely at least badly damaged.
But Pickaxe Mountain was not considered a major bombing target during the war between Israel and Iran last year.
It was also not attacked during the wave of fighting involving the US that began in February. Officials have nevertheless long feared that Iran could use the tunnels to store or manufacture nuclear equipment and establish a small uranium-enrichment facility capable of producing fissile material.
Activity at the site has continued steadily over the past 15 months, including truck traffic, tunnel reinforcement and the construction of a security perimeter, according to the Institute for Science and International Security (ISIS), a research organization specializing in nuclear and nonproliferation issues.
“It is likely that Iran has moved centrifuges into the tunnels” at Pickaxe Mountain, David Albright, the institute's president, told the newspaper.
Little is known about the complex located inside the mountain, but experts believe it is still under construction and estimate it is buried almost 100 meters inside the mountain.
Construction of the facility at Pickaxe Mountain began in 2020, according to the ISIS thinktank, after what Iranian authorities reported at the time as an explosion caused by an act of sabotage at the Natanz facility.
In September of that year, Iran’s then nuclear chief, Ali Akbar Salehi, said the country had started building a “modern, larger and more comprehensive hall in all dimensions in the heart of the mountain near Natanz” for making advanced centrifuges. These machines spin uranium at high speeds to enrich it and produce nuclear fuel.
ISIS, in its report, said its assessment “is that the facility is not yet operational, but construction continues,” and that it was unclear when it could be operational, based on satellite imagery alone.
The thinktank said it is also unclear if Iran still plans on installing a large-scale assembly facility there.
“Nonetheless, if Iran starts to rebuild its centrifuge manufacturing capability, it could plan to install a smaller centrifuge assembly facility in Pickaxe Mountain able to serve a nuclear weapons program,” the ISIS report said.
Earlier, IAEA said Iran has denied inspectors access to the site and has not provided information about activities or plans there.
The Agency’s Director General Rafael Grossi said in March that Iran had informed the agency in 2021 of its “intention to conduct nuclear activities” at the site.
An Israeli army official familiar with efforts to select targets for attack expressed concern that airstrikes during the latest war had not sufficiently damaged work related to nuclear weapons. The official said more remained to be done, including at Pickaxe Mountain.
The US has intensified its strikes on Iran over the past 10 days. US President Donald Trump said Washington was prepared to attack Pickaxe Mountain.
“Pickaxe is a possible target for a nice big fat shot right near the front door,” Trump told conservative broadcaster Hugh Hewitt on July 13. It was the first time Trump had explicitly identified the site as a possible target, although he had previously referred to an underground Iranian facility buried in granite.
The limited information available about Iranian activity there suggests that it would pose significant challenges to any airstrike.
