The UN nuclear watchdog has detected signs of renewed activity around Iran’s heavily fortified Pickaxe Mountain complex, a secretive underground site that inspectors have never entered, Bloomberg reported Thursday.
International Atomic Energy Agency Director General Rafael Mariano Grossi told Bloomberg Television that satellite and other remote imagery showed movement around the facility, but stressed that the agency has no evidence establishing what is taking place inside.
“There are some indications that there is movement around this construction site,” Grossi said. “We don’t have any concrete information as to activities that may be taking place there.”
The site has come under renewed scrutiny as tensions over Iran’s nuclear program intensify. U.S. President Donald Trump has publicly referred to Pickaxe Mountain at least twice over the past week, signaling that Washington is closely watching developments there.
“We notice there’s a little activity at Pickaxe,” Trump said Wednesday at a Republican rally. “I would advise Iran not to get cute because we will have to hit them very hard.”
According to Bloomberg, the IAEA’s latest observations come as its board of governors has referred Iran’s nuclear file to the UN Security Council over Tehran’s failure to comply with requirements surrounding its nuclear activities.
The agency is also still unable to account for Iran’s stockpile of uranium enriched to near-weapons-grade levels. Inspectors have not verified its condition or location since June 2025, when Israel and the United States attacked major Iranian nuclear facilities.
Pickaxe Mountain, located in the Zagros Mountains roughly 220 kilometers south of Tehran, began drawing particular attention after an Iranian centrifuge workshop was sabotaged six years ago. Iran subsequently said it intended to move sensitive nuclear-related infrastructure underground to protect it from attack.
“They said at the time, ‘we are going to put everything in tunnels, inside a mountain,’” Grossi told Bloomberg. “This was going to be impermeable and protected from attacks.”
The United States and Israel have demanded that Iran dismantle its centrifuge program and end uranium enrichment. Centrifuges are used to separate uranium isotopes, a process required to produce fuel for civilian reactors but also essential to producing material for nuclear weapons at much higher enrichment levels.
The latest censure of Iran at the IAEA adds another layer of pressure to an already volatile confrontation. Bloomberg noted that the resolution could increase the possibility of renewed military action against Iranian nuclear facilities, particularly after Trump repeatedly framed preventing Tehran from obtaining a nuclear weapon as a central reason for confronting Iran.
International Atomic Energy Agency Director General Rafael Mariano Grossi
(Photo: Joe Klamar / AFP)
Tehran, meanwhile, has accused Western governments of using the IAEA to prepare the ground for military action.
In a diplomatic note circulated this week and cited by Bloomberg, Iran pointed to June 2025, when Israel launched attacks on the Islamic Republic one day after the IAEA found Tehran in non-compliance with its nuclear obligations.
“The aggressions of the Israeli regime and America against Iran just a few hours after its adoption, are solid proofs of the sponsors’ hidden agenda,” Iran’s representative to the agency wrote, urging diplomats to “condemn the unlawful attacks.”
Grossi said the dispute with Iran is unfolding against a broader and increasingly dangerous global nuclear backdrop, as more governments reconsider the role nuclear weapons could play in their security strategies.
“It has to do with a world where there is more conflict, where there are more wars,” Grossi said.
He warned that wider nuclear proliferation would dramatically increase the chances that such weapons would eventually be used.
“There would be nuclear weapon use for sure, 100% guaranteed,” Grossi said.