Israeli intelligence believes Iran relocated thousands of uranium enrichment centrifuges into tunnels deep inside a mountain following last year's conflict with Israel, The Wall Street Journal reported on Monday, citing Israeli and U.S. officials.
Israel shared the intelligence assessment with the United States, saying the centrifuges were transferred to a site known as Pickaxe Mountain after the 12-day war in June 2025, when U.S. and Israeli airstrikes targeted Iran's three main nuclear facilities.
An Israeli military official familiar with the campaign told the newspaper the airstrikes did not sufficiently target facilities linked to Iran's nuclear weapons program and warned that "there is more work to do," including at Pickaxe Mountain.
According to the report, as Israel's objectives increasingly diverged from those of the United States, Prime Minister Benjamin Netanyahu sought to persuade President Donald Trump to resume large-scale strikes on Iran to further delay Tehran's nuclear weapons program and reconstruction efforts.
The United States has intensified its military operations over the past 10 days. Trump said last week the U.S. would be prepared to strike Pickaxe Mountain, located about 1.5 kilometers (1 mile) south of Iran's Natanz nuclear facility.
"Pickaxe is a possible target for a nice, big, fat shot right near the front door," Trump told conservative radio host Hugh Hewitt last week. It was the first time he publicly identified the site as a potential target, although he had previously referred to an underground Iranian facility buried beneath granite.
The site, known in Iran as Mount Kolang Gaz La, has been monitored by U.S. and Israeli intelligence for years. Limited publicly available information suggests the underground complex would present a major challenge for any airstrike.
US President Donlad Trump
(Photo: AP)
Located near Natanz, the facility was intended to replace Iran's underground centrifuge assembly plant, which was heavily damaged in a 2020 explosion widely believed to have been an act of sabotage.
The Washington-based Institute for Science and International Security said construction activity has continued steadily over the past 15 months, including truck movements, tunnel reinforcement and expanded security infrastructure. The institute also reported work around an older tunnel network dating to 2007 that Iran has since sealed.
"It is likely that Iran has moved centrifuges into the tunnels" at Pickaxe Mountain, David Albright, the institute's president, told the newspaper. Experts estimate the underground complex extends roughly 90 to 137 meters (295 to 450 feet) beneath solid rock and is large enough to house multiple nuclear-related facilities.
Nate Swanson, who served on the U.S. National Security Council during the Biden administration, said Iran's history of covert nuclear activity makes any undeclared work at such a hardened underground site especially concerning.
"A clandestine breakout is the worst-case scenario," Swanson said. "We don't know what Iran's intentions are, but the fact that we cannot verify what is happening at this site underscores how problematic the status quo is. We need the International Atomic Energy Agency to inspect these places."
Pickaxe Mountain was not a primary target during last year's Israel-Iran war and was not struck during the latest round of U.S. military operations that began Feb. 28. However, officials and nuclear experts have long warned that Iran could use the tunnels to store or manufacture nuclear equipment or establish a small enrichment facility capable of producing weapons-grade fissile material.
Iran has consistently denied seeking nuclear weapons. However, it has produced roughly 450 kilograms (992 pounds) of uranium enriched to 60% purity, close to weapons-grade levels.
Analysts cautioned that moving centrifuges to Pickaxe Mountain does not necessarily mean Iran has established an enrichment facility there. Tehran may instead have relocated surviving centrifuges after last year's war to protect them from future attacks.
It remains unclear where the centrifuges originated. They may have been reserve machines stored at Iran's main nuclear sites. The International Atomic Energy Agency has said Iran has denied inspectors access to the site and has not provided information about activities or plans there. IAEA 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.
Iranian Foreign Minister Abbas Araghchi and the IAEA did not respond to requests for comment from The Wall Street Journal. The White House referred the newspaper to Trump's public comments on the site.