The International Atomic Energy Agency has confirmed construction activity at Pickaxe Mountain, one of Iran's most secretive nuclear facilities, a deeply buried tunnel complex located roughly 2 km south of Iran's main uranium enrichment plant at Natanz. IAEA Director General Rafael Grossi announced the findings on September 10 based on satellite imagery showing fresh building work at the site.
On the same day as Grossi's announcement, the IAEA's Board of Governors voted to refer Iran to the UN Security Council for non-compliance with nuclear safeguards. The referral marks the first such action in two decades.
The Pickaxe Mountain Facility
Pickaxe Mountain, known as Kuh-e Kolang-e Gazela in Farsi, is an underground tunnel complex carved into a mountain near Natanz. The facility features hardened portals and advanced underground tunnel networks with chambers considerably deeper than known facilities like Fordow.
The IAEA has never been granted access to the facility despite years of requests from Iran. All information about current activity comes from satellite imagery.
Construction at the site accelerated significantly after 2020, following sabotage attacks on the Natanz complex that destroyed an above-ground centrifuge workshop. The Center for Strategic and International Studies identified a surge in construction activity throughout 2026, noting unprecedented levels of road activity around the site. The Institute for Science and International Security has similarly flagged increased portal hardening and expanded security perimeters.
Verification Challenges
Iran's non-compliance deepened since June 2025, when military strikes disrupted the IAEA's verification efforts at Iranian nuclear sites. The agency has since operated with severely limited visibility into Iran's nuclear program, unable to verify enrichment levels, stockpile sizes, or the purpose of new construction.
Without inspectors on the ground, the international community lacks clarity on whether Iran is enriching uranium to weapons-grade levels. Iran has already demonstrated the technical capability to enrich uranium to 60% purity, described as a short technical step from the 90% needed for a weapon.
International Response
The Security Council referral opens the door to new international sanctions, though Russia and China, both permanent Security Council members with veto power, have historically been reluctant to support aggressive measures against Tehran.
The escalation sends ripple effects through global energy markets. Iran holds some of the world's largest proven oil reserves, and any tightening of sanctions or military confrontation in the region could affect energy supply at a time when markets remain sensitive to geopolitical shocks.
