NATANZ — Iran transferred thousands of uranium enrichment centrifuges to underground facilities inside Natanz's Pickaxe Mountain in late 2025. Israeli and U.S. officials assessed that Iran moved the centrifuges to ensure continued uranium enrichment production.

The transfer of centrifuges occurred following the 12-day war in June 2025. During that conflict, American and Israeli strikes targeted three of Iran’s main nuclear sites in an operation the U.S. called "Midnight Hammer."

Pickaxe Mountain is located south of the Natanz nuclear complex. The Pickaxe Mountain tunnel facility was not targeted in the June 2025 conflicts, according to the Institute for Science and International Security. Satellite imagery shows the Pickaxe Mountain complex is carved to a depth of more than 100 meters below bedrock.

Tehran claimed the Pickaxe Mountain site is intended solely as a factory for the production and assembly of advanced centrifuges, not as an active enrichment facility. Iranian authorities are preventing International Atomic Energy Agency inspectors from entering the Pickaxe Mountain site.

IAEA Director-General Rafael Grossi demanded that Iran provide answers regarding its activities at the Pickaxe Mountain site. He said the agency requires transparency concerning the underground complex. U.S. President Donald Trump threatened to eliminate the Pickaxe Mountain site.

The relocation of thousands of centrifuges to a fortified underground site represents a significant structural change in Iran's nuclear infrastructure following the June 2025 war. The depth of the facility, carved more than 100 meters below bedrock, suggests an effort to harden the program against future aerial strikes similar to "Midnight Hammer." The lack of access for international inspectors prevents verification of Tehran's claim that the site serves only as an assembly factory rather than an active enrichment center. This opacity complicates diplomatic efforts to monitor nuclear activities and has drawn direct demands for answers from the IAEA leadership. The threat from the U.S. President indicates that the site remains a focal point of geopolitical tension and potential future military targeting.