Iran relocated thousands of centrifuges into tunnel networks beneath Pickaxe Mountain near Natanz last autumn, preparing the site for uranium enrichment to 90 percent, according to Israeli intelligence assessments. The mountain facility, buried up to 600 meters beneath solid granite, is believed to be beyond the reach of bunker-busting munitions such as the GBU-57.
The transfer followed U.S.-Israeli strikes in June 2025 during a brief war that destroyed three Iranian nuclear sites, including Natanz's above-ground enrichment plant, which was destroyed, and its underground facility, which sustained heavy damage. The Institute for Science and International Security has documented truck traffic, tunnel reinforcement, and new security perimeters at Pickaxe Mountain since last year.
President Donald Trump has repeatedly threatened to strike the site, saying the United States would destroy it. Iran has maintained since 2020 that the location is merely an advanced centrifuge assembly workshop.