Construction activity at Iran's underground Pickaxe Mountain nuclear base has significantly increased this year, according to satellite imagery analysis by the Center for Strategic and International Studies (CSIS). This surge in activity coincides with repeated threats from former President Donald Trump to strike the facility.
The CSIS report indicates a "clear surge in construction activity in 2026" characterized by the hardening of portal accesses, paving of internal road networks, and reinforcement around access areas. This work began accelerating in October 2025, around the time Israeli intelligence reportedly warned the Trump administration that Iran was transferring uranium centrifuges and components to the base. While CSIS could not confirm the Israeli claims, the observed construction suggests Iran is fortifying the site following last year's strikes by the U.S. and Israel on Iranian nuclear facilities. The focus appears to be on repairing entrances damaged in those attacks and preventing future access.
Pickaxe Mountain is located more than 300 feet underground beneath Kolang Mountain, a depth that presents a significant challenge for U.S. military capabilities. The most powerful U.S. bunker-buster bomb, the GBU-57, has a penetration capability of approximately 200 feet, falling short of the base's deepest levels. This depth protects the facility from current U.S. ordnance.
Despite a temporary cease-fire memorandum of understanding with the U.S., researchers found that construction at Pickaxe Mountain continued at a high rate, which the CSIS noted was against the terms of the truce. The facility is reportedly still not capable of enrichment work, but internal construction is ongoing.
Former President Trump has publicly stated his intention to strike the base, telling reporters, "We may hit Pickaxe very soon." However, destroying the deeply buried facility poses a difficult challenge. The U.S. is reportedly developing next-generation penetrator bombs that might be capable of reaching the site, though the development status and readiness of these weapons remain unclear.
Another potential strategy involves attacking and burying the base's entrances, similar to actions taken against Iranian missile facilities. However, experts have noted Iran's demonstrated ability to excavate and reopen such sites after being targeted.
