Underground site not inspected by IAEA
Israeli intelligence believes Iran moved thousands of uranium-enrichment centrifuges into tunnels deep inside the underground Pickaxe Mountain site last fall, Israeli and U.S. officials told The Wall Street Journal, a development that would heighten concerns that Tehran could reconstitute its nuclear program after sustaining heavy damage to its declared facilities.
Israel passed the intelligence findings to the U.S., according to the officials, saying the centrifuges were transferred to the site last fall after the 12-day war in June 2025 when American and Israeli strikes pummeled Iran’s three main nuclear sites. The move suggests Iran has preserved enrichment capability in a location that, at an estimated 300 to 450 feet deep beneath solid rock, has so far escaped the bombing campaigns.
Pickaxe Mountain, known locally as Mount Kolang and located near one of Iran’s main nuclear installations, was originally commissioned as an underground replacement for a centrifuge-assembly facility at Natanz that was badly damaged after a July 2020 explosion widely attributed to sabotage. Construction at the mountain began shortly after that attack.
As Israel’s war aims have increasingly diverged from the U.S.’s, Prime Minister Benjamin Netanyahu has tried to persuade President Trump to resume all-out attacks on Iran to further set back Tehran’s weapons programs and rebuilding effort, according to officials. The U.S. has stepped up attacks in the past 10 days, and Trump said the U.S. was prepared to attack Pickaxe Mountain.
Trump told conservative broadcaster Hugh Hewitt on July 13 that Pickaxe is “a possible target for a nice big fat shot,” in what officials described as the first time he has explicitly discussed the site as a target, though he has previously mentioned an Iranian underground location buried in granite. MSI previously reported that Trump threatened to bomb Iran’s Pickaxe Mountain nuclear site on July 16.
Activity at the site has continued steadily for the past 15 months, according to the Institute for Science and International Security, a think tank focused on nuclear and nonproliferation issues. Researchers observed truck traffic, tunnel reinforcements, and a security perimeter springing up, as well as work around an older tunnel network dating from 2007 that Iran has since sealed up.
“It is plausible that Iran moved centrifuges into the tunnels” in Pickaxe, said David Albright, the institute’s president.
An Israeli military official familiar with the targeting effort expressed concern that the recent war’s airstrikes had not sufficiently targeted nuclear-weapons-related work, saying that there was more work to be done, including at Pickaxe Mountain.
Iran has denied ever seeking nuclear weapons, but it has produced about 1,000 pounds of 60% enriched uranium, near weapons-grade. Iran has provided the IAEA no information about its work or plans at the Pickaxe Mountain site, the nuclear agency has said. Director General Rafael Grossi said in March that Iran in 2021 announced its “intention to have nuclear activity” at the site.
The placement of centrifuges at Pickaxe does not necessarily mean Iran is building an enrichment site there, officials and experts cautioned. After the June 2025 bombings, Tehran may have put its surviving centrifuges there to minimize their risk of destruction. Iran’s foreign minister and the IAEA did not respond to requests for comment.
Nate Swanson, a U.S. National Security Council director for Iran in the Biden administration, said Tehran’s history of covert nuclear activity means any undeclared activity in a hardened underground site is cause for concern.
“A covert breakout is the worst-case scenario. We don’t know what Iran’s intentions are, but the fact that we can’t verify this site underscores how problematic the status quo is,” Swanson said. “We have to have the IAEA in there to inspect these things.”