Iran has intensified construction work at a secret underground nuclear facility inside Pickaxe Mountain near Natanz, according to satellite imagery analysis published by CNN. The facility, buried beneath a granite mountain 225 kilometers south of Tehran, has become a focal point of conflict as Washington evaluates weapons to target deeply buried structures.
Analysis by the Center for Strategic and International Studies (CSIS), released ahead of an official report, revealed a marked acceleration in construction activity at the complex throughout 2026. Experts at the Washington-based national security think tank assessed that the underground complex is likely designed as a protected sanctuary to preserve or develop elements of the Iranian nuclear program.
Israeli intelligence services suggested that Iranian authorities may plan to transfer centrifuges to the subterranean site to safeguard uranium enrichment operations from external attack. The facility sits just two kilometers south of the main Natanz nuclear complex, long established as Iran's primary center for uranium enrichment using high-speed centrifuge cascades.
United States President Donald Trump issued repeated warnings regarding the site, stating last week that American forces might strike Pickaxe Mountain very soon. Trump asserted that intelligence agencies are closely monitoring the location and tracking everyone moving within the area.
Pentagon tests bunker busting weapons
The dense granite formation surrounding Pickaxe Mountain poses severe military hurdles for offensive operations, as defense analysts believe the natural rock shielding may withstand the heaviest conventional bombs in the American arsenal. In response, the United States Department of Defense has initiated urgent efforts to evaluate new weapon technologies capable of penetrating extreme subterranean depths.
Four days prior to the launch of Operation Epic Fury, a specialized Pentagon unit responsible for countering weapons of mass destruction approved an emergency contract valued at 1.2 million dollars. The contract, managed by the Defense Threat Reduction Agency (DTRA), funded urgent repairs to a subterranean testing facility at the White Sands base in New Mexico.
Federal database documentation posted on February 27, one day before military operations commenced, specified that work at White Sands was ordered under an urgent national security directive to be completed within two to three weeks. The objective involved a live-fire test to evaluate classified strike capabilities against emerging subterranean threats.
Sources informed CNN that the White Sands project directly related to developing methods for destroying Iran's most deeply buried underground facilities. White Sands Missile Range, located in the desert of southern New Mexico, serves as a primary United States military venue for testing advanced missile systems, weapons of mass destruction defenses, and high-explosive penetration ordnance.
Lessons from previous strikes
The renewed focus on subterranean targets follows earlier military actions under Operation Midnight Hammer in June 2025, when United States forces launched strikes against Iranian nuclear installations. While those attacks inflicted substantial damage on surface structures and shallow infrastructure, military leadership acknowledged significant limitations against heavily fortified underground sites.
A top American military general informed Congress following the 2025 strikes that existing bunker buster munitions were incapable of completely destroying Iran's deeply buried nuclear facility at Isfahan. Isfahan, a major city in central Iran, hosts extensive nuclear research facilities, conversion plants, and underground storage sites integral to the national nuclear infrastructure.
The primary conventional weapon currently deployed by the United States Air Force for hardened targets is the GBU-57 Massive Ordnance Penetrator (MOP). The 30,000-pound precision-guided bomb is engineered to penetrate up to 200 feet of earth and reinforced concrete before detonating, but military planners estimated that even the MOP may prove insufficient against the granite geology at Pickaxe Mountain.
Military commanders concluded that standard MOP weapons require technological upgrades or replacement to breach natural granite shields. Consequently, the United States Air Force has initiated formal procurement processes to develop a next-generation penetrating bomb intended to replace the existing MOP arsenal with enhanced deep-burrowing capabilities.
Satellite imagery shows site progress
Satellite imagery reviewed by CNN showed excavation operations at the DTRA test location at White Sands beginning between February 16 and February 18. Work at the specialized facility, known as the Alternate Seismic Hardrock in Situ Test Site, continued until mid-March before activity concluded. Like Pickaxe Mountain, the New Mexico test site is constructed directly within a solid granite geological environment.
CNN reported that it could not independently confirm whether the scheduled live-fire weapon test occurred or determine the full operational scope of the White Sands site modifications.
Regarding the Iranian complex, CSIS analysts identified three potential operational roles for Pickaxe Mountain within Tehran's broader nuclear program. The underground site could serve as a centrifuge assembly facility, a uranium enrichment plant, or a fortified location for nuclear weapons research, such as converting enriched uranium gas into solid metallic form.
Infrastructure details and readiness
Recent satellite imagery indicates that construction work at Pickaxe Mountain has shifted from initial heavy excavation to internal structural build-out and external infrastructure fortification. Analysts noted increased vehicle traffic, reinforcement and extension of tunnel entryways, paving of internal access roads, and construction of hardened access control points around the perimeter.
In addition, satellite photographs revealed that a security perimeter fence completely enclosing the facility grounds has been constructed. Despite the visible structural progress, CSIS experts estimated that the subterranean site is likely not yet operational or equipped to conduct active uranium enrichment operations.
The development of Pickaxe Mountain presents a growing strategic dilemma for United States military commanders seeking to counter hardened nuclear infrastructure. As Iran continues to invest heavily in deep underground protection, the subterranean complex remains a central focus in the ongoing military confrontation over Tehran's nuclear program.
