Deep Under Granite: Construction Surges at Suspected Iranian Nuclear Site

Satellite imagery analysis recently published by the Center for Strategic and International Studies (CSIS) reveals a dramatic surge in construction activity at Pickaxe Mountain (Kuh-e Kolang Gaz La), a deeply buried underground facility near Iran’s primary Natanz nuclear complex.

Located roughly 140 miles south of Tehran, the location has long drawn intense scrutiny from international intelligence agencies who view it as a potential safe haven designed to shield Iran’s critical nuclear work from external strikes.

Key Highlights from the CSIS Analysis

By comparing six years of high-resolution satellite imagery, CSIS researchers observed several major developments in 2026:

• A Shift from Excavation to Internal Construction: Rather than expanding the footprint through digging, recent activity shows workers reinforcing access portals, paving internal road networks, and flattening excavated dirt—indicating work has likely moved inside the mountain.
• Record Road Activity: Imagery captured throughout July and August showed more road traffic leading to and from the site than at any previous point in its history.
• Unclear Purpose: While researchers outline three main potential uses—a centrifuge assembly shop, a uranium enrichment plant, or a facility for uranium metal conversion—public data cannot yet confirm what is inside.
• Not Yet Operational for Enrichment: Analysts noted that continuous heavy construction, paired with a lack of specific non-construction equipment or specialized security infrastructure, indicates the site is likely not yet capable of active uranium enrichment.

Why Is Pickaxe Mountain Significant?

The history of Pickaxe Mountain traces back to 2020, when Iran announced plans to construct a secure underground replacement following a suspicious explosion and fire at an aboveground centrifuge workshop in Natanz.

What makes Pickaxe Mountain unique—and challenging for foreign military planners—is its geography. Buried deep beneath solid granite rock (estimated between 80 to 100 meters underground), the complex presents an extraordinarily difficult target for conventional weapons, including specialized “bunker buster” ordnance.

Rising Geopolitical Tensions

The surge in construction arrives amid heightened international friction:

1. U.S. Rhetoric: U.S. President Donald Trump publicly addressed the location, suggesting the U.S. was closely monitoring activity and keeping strike options on the table to prevent Iran from obtaining nuclear weapons.
2. IAEA Transparency Requests: The International Atomic Energy Agency (IAEA) has requested detailed information and physical access to inspect Pickaxe Mountain, but Iranian officials have yet to fulfill those requests.

What’s Next?

While the underground complex remains a flashpoint in Middle East security discussions, experts emphasize that monitoring satellite telemetry will remain vital. As internal construction continues, intelligence agencies will be watching closely for indicators that equipment, such as centrifuges, is being moved into the hardened facility.

Iranian president responds to reports of construction at nuclear facility

This video provides important context on how Iranian leadership addresses reports and international scrutiny regarding underground construction near the Natanz nuclear site.