New Satellite Imagery Analysis Reveals an Uptick in 2026 Construction Activity at Pickaxe Mountain

As depicted in Figure 1, Phase 1 (2020–April 2024) was marked by heavy construction and initial site buildout. Phase 2 (April 2024–January 2026) was relatively consolidated, with less change detected across the facility aside from the changes noted in late 2025. However, SAR change detection analysis during Phase 3 (January 2026–present) registered heavy usage across every road corridor simultaneously and increased hardened surface returns near portal accesses and road corridors. Phase 3 represented the most activity of this kind since the initial construction of the facility and is indicative of increased utilization of the site rather than new excavation.

This analysis was supplemented by VHR imagery acquired from Airbus of Pickaxe Mountain from July 9, 2026, and Satellogic Imagery from August 9, 2026, which corroborates the previous findings: The surge corresponds to the raising and hardening of the portal accesses, hardening of the internal road network, reinforcement around access areas, and the flattening and removal of excavation spoil piles. Together, these signals indicate a transition from excavation toward probable internal construction and continued exterior reinforcement.

The first campaign returned significant change in the detection of bare soil, likely because roads were being constructed during this phase. The rising radar signatures with falling amounts of bare soil across every corridor in Phase 3 indicate hard-surface returns—such as vehicles, materiel, compaction, or traffic—over ground that is no longer being freshly exposed. Overlaying Sentinel-1 SAR with 10-meter optical imagery from Sentinel-2 reveals these changes across the road networks at Pickaxe Mountain in the graphic below.

Analysis of VHR Airbus optical imagery (below) resolves what the SAR change detection indicated: new concrete surfacing over roads and exterior portal accesses, a noted decrease in spoilage piling and evidence of removal, and continued construction activity. The south and east portal entrances are more heavily hardened in July 2026 than they were in September 2025. There is site-wide evidence of the removal of excavation spoilage, which is typical of a construction site transitioning from a cut to a buildout phase and is a probable indication that construction shifted toward the internal construction of the underground facility, though external reinforcement of east and west portal access is still ongoing. No change was observed at the Natanz Nuclear Facility itself, consistent with the surge in activity observed via Sentinel data being specific to the Pickaxe underground complex.

Other analysts have concluded Iranian construction activity continued at Pickaxe Mountain during the June 17 memorandum of understanding (MOU) between Iran and the United States. That MOU stated that “the Islamic Republic of Iran will maintain the current status quo of its nuclear program.” CSIS imagery analysis confirms that construction activity continued at a high rate during the period covered by the MOU.

Pickaxe’s Defenses

It is difficult to assess with a high degree of accuracy the depth of the underground facility at Pickaxe Mountain Some open-source estimates claim that the facility is between 80 and 100 meters deep. However, these estimates rely on measuring the amount of spoil, or dirt removed from the underground tunnel. While satellite imagery can provide some insights into the volume of dirt removed by measuring spoil piles, it does not provide insight into the internal design of the facility as tunnels drilled horizontally, upward, or downward would likely accumulate the same volume of spoilage. Despite these limitations to internal analysis, detailed analysis of the external facility at Pickaxe Mountain reveals an extensive and heavily fortified underground facility buried deep into a granite mountain.

It is incredibly difficult to destroy a facility such as Pickaxe Mountain through conventional external kinetic force. While the United States possesses large munitions, even the heaviest “bunker buster” bombs have limits. The largest conventional bunker buster in the United States arsenal is the GBU-57 Massive Ordnance Penetrator, which can only be operationally delivered by the B2 stealth bomber. This 30,000-pound precision-guided munition, which carries a 5,000-pound explosive warhead, can reportedly penetrate 60 meters into the ground before it detonates with a delayed fuse.

During Operation Midnight Hammer, the United States Air Force dropped 12 Massive Ordnance Penetrators at Fordow, creating six craters on top of a ventilation shaft that led into the underground centrifuge hall. This strategy, which is called “double tapping,” begins with dropping one bomb on the ground to create a hole. The second Massive Ordnance Penetrator then falls directly into the crater of the first bomb, coupling the blast more deeply underground to channel the shock wave into the earth.

The nuclear facility at Fordow was reportedly buried at least 80 meters deep, beyond the upper limits of the Massive Ordnance Penetrator’s capabilities. However, Fordow contained a structural weak point: ventilation shafts that allowed blast waves to channel directly into the underground facility. Additionally, it is clear from the precision of the attack on Fordow that the United States and Israel had a significant amount of intelligence about their target, possibly including schematics and blueprints of the facility. While ventilation is a requirement of any underground facility, it is unclear from open sources if ventilation shafts at Pickaxe Mountain are similar structural weak points, as Iran would likely seek to apply lessons learned from Operation Midnight Hammer.

If the United States decides to attack Pickaxe Mountain, dropping Massive Ordnance Penetrators with B2 bombers may not actually complete the job. Furthermore, the United States possesses a limited inventory of Massive Ordnance Penetrators and is currently trying to restock that inventory after Operation Midnight Hammer. The Pentagon may decide that a more effective attack on Pickaxe Mountain involves targeting and collapsing tunnel entrances with cruise missiles, rather than attempting to cause structural damage to the underground facility itself. This is the same approach that the United States took for the Isfahan underground nuclear facility in June 2025, when the tunnel entrances were struck with multiple Tomahawk cruise missiles. As a result, Iran may seek to further fortify the tunnel entrances at Pickaxe Mountain. Optical satellite imagery from after President Trump’s statements is not commercially available at the time of publication.

Destroying Pickaxe Mountain will be a scientific and targeting challenge. It is an underground fortress buttressed by granite. It is one of the only facilities in Iran’s nuclear program that the United States has not yet struck. Structurally degrading Pickaxe Mountain requires more than just kinetic force—it takes actionable high-confidence intelligence and sophisticated mathematical modeling. The U.S. hesitation to strike Pickaxe Mountain and Isfahan with bunker busters likely reflects operational caution. Nevertheless, the United States appears poised to target Pickaxe Mountain, with President Trump claiming “we’ll be hitting that area pretty soon. And very heavily.”

The Challenge of Iran’s Clandestine Nuclear Facilities

This multisource imagery analysis of Pickaxe Mountain reveals more road activity in 2026 than the last six years. The imagery analyzed here can not substantiate nor refute claims that Iran moved uranium enrichment centrifuges into Pickaxe Mountain. Given the level of construction activity at the site, there is reason to doubt that Iran is conducting uranium enrichment at the facility right now.

Ultimately, Pickaxe Mountain is just one of many challenges that the United States faces in Iran. Tehran has many underground facilities that are difficult to strike, including the underground facility at the Isfahan nuclear complex. Prior to Operation Midnight Hammer, IAEA Director General Rafael Grossi was scheduled to visit the underground facility at Isfahan to view a third uranium enrichment site that Iran was allegedly constructing.

Iran operates numerous other underground facilities across the country. Even if the United States can destroy or disable Pickaxe Mountain, Tehran’s nuclear aspirations are unlikely to change any time soon. Military operations in Iran must ultimately serve U.S. political and security objectives. If the United States’ goal is to prevent Iran from ever developing a nuclear weapon, repeatedly bombing Iran every few months is insufficient and unsustainable. Ultimately, a verifiable diplomatic solution is likely the only lasting resolution to restrict Tehran’s nuclear ambitions.

Joseph Rodgers is deputy director and fellow in the Project on Nuclear Issues at the Center for Strategic and International Studies (CSIS) in Washington, D.C. Douglas Comstock is fellow for satellite imagery analysis and open-source intelligence at CSIS.