The Pickaxe Mountain site, located near Iran's Natanz nuclear complex about 140 miles south of Tehran, has been the subject of sustained attention from intelligence agencies, which view it as a likely location for protecting future Iranian nuclear programme activities. A new analysis by the Center for Strategic and International Studies (CSIS), shared exclusively with CNN ahead of its publication, found “a clear surge in construction activity” at the site in 2026 after reviewing six years of satellite imagery.
The CSIS analysts said the underground facility was “likely” designed as a safe haven for Iran's nuclear programme. Construction activity intensifies at underground siteAccording to the CSIS analysis, construction at Pickaxe Mountain has shifted from active excavation towards what is probably internal construction and continued reinforcement of the site's exterior.
The site has seen “more road activity” in 2026 than ever before, the analysts said. The work has included raising and hardening tunnel portal accesses, paving the internal road network, reinforcing areas around the accesses and flattening and removing dirt excavated during tunnel construction.
The facility is “likely” designed for one of three purposes linked to Iran's nuclear programme, according to the analysis. It could serve as a centrifuge assembly facility, an enrichment facility or a safe haven for other “nuclear weapons-relevant” activities such as uranium metal conversion.
Israeli intelligence has suggested that Iran may be seeking to move centrifuges to Pickaxe Mountain as part of uranium enrichment efforts. “We may hit Pickaxe very soon,” Trump told reporters last week, adding that “we know everybody that’s moving” at the site.
Trump had also said the US could “hit” Pickaxe Mountain if it detected activity there. The US military maintains operational plans for strikes against Pickaxe Mountain, according to a source familiar with the matter cited by CNN.
The site was part of a target package considered earlier this summer when Trump was threatening to escalate the conflict with Iran. The strike plan involved some of the largest bombs in the US arsenal, the source said, although it remained unclear whether those weapons could penetrate deeply enough underground to destroy whatever Iran may have moved there.
The granite mountain presents a difficult target even for the Pentagon's “heaviest non-nuclear” bombs, according to the CSIS team. US works on ways to hit deeply buried sitesThe US has also been working on ways to target deeply buried underground facilities.
