Tehran is accelerating defenses at its most vital surviving nuclear facility near Natanz, leveraging delays in potential US or Israeli strikes to render the underground complex nearly impervious to attack. High-resolution satellite images reveal a flurry of construction activity at the Kolang-Gaz La Mountain tunnel site, also known as Pickaxe Mountain, as analyzed by the Institute for Science and International Security (ISIS).
According to a Jerusalem Post article by Yonah Jeremy Bob published February 12, the imagery from February 10 shows Tehran pouring concrete over the western tunnel entrance extension and leveling rock and soil at eastern portals, with dump trucks, cement mixers, backhoes, and cranes swarming the area. These reinforcements add overburden material like extra rock, soil, or concrete, bolstering protection against airstrikes that devastated most Natanz facilities—including existing centrifuges—during the Israel-Iran War in June 2025. Fordow, another deeply buried site bombed by US bunker-busters, sat under a 960-meter mountain, but Pickaxe Mountain towers 650 meters taller at 1,608 meters above sea level, offering superior shielding even pre-war.
The facility, construction of which began around 2021 and was publicly exposed by ISIS and the Jerusalem Post in 2022, remains non-operational, evidenced by persistent heavy machinery and limited utilities like a single ventilation shaft and power lines. Iran has publicly linked it to rebuilding an advanced centrifuge assembly plant destroyed in 2020, but its vast scale raises alarms it could host uranium enrichment or covert weaponization efforts. Smaller vehicles and covered transports spotted recently suggest interior outfitting is underway, potentially expanding capabilities lost when Natanz, Fordow, and Isfahan were crippled last summer.
This rush coincides with stalled US threats amid December 28 protests in Iran, transforming an already formidable target—deemed harder to destroy than Fordow by ISIS president David Albright—into an even greater challenge. While current infrastructure may limit full nuclear functions, Tehran's investments signal determination to safeguard its program against renewed military pressure from Washington or Jerusalem.