What is Pickaxe Mountain, Iran's secretive nuclear site in Trump's sights?

A mysterious underground site deep inside Iran's Zagros mountain range, believed by some experts to be either a covert uranium enrichment facility or a secret storage site for near-weapons-grade uranium, has become US President Donald Trump's latest target.

At the centre of Trump's remarks is Pickaxe Mountain, also known as Kuh-e Kolang Gaz La. The site lies in the Zagros mountain range, about two kilometres from the heavily damaged Natanz nuclear facility, which was hit by US bunker-buster bombs in June last year.

However, Reuters and The Washington Post, citing US officials and experts, reported that the vast tunnel complex beneath Pickaxe Mountain is believed to be beyond the reach of bunker-buster bombs.

Experts estimate the underground halls are deeper than the weapons' penetration capability of about 200 feet of earth and rock, or 20 feet of reinforced concrete.

On Monday, Trump signalled that Pickaxe Mountain could be the next target.

"We're going to take out Pickaxe Mountain. Tell the Iranians to be ready," Trump said during an interview on The Hugh Hewitt Show.

"We're watching Pickaxe Mountain closely. We see no activity there. They're not doing well with their nuclear situation. Every time we hear about it, we blow it up. So they don't like talking about it. But we'll probably give Pickaxe a shot relatively soon," he added.

Trump's latest threat comes despite his repeated claims that last year's US strikes had "obliterated" Iran's nuclear programme. Yet Pickaxe Mountain has remained under scrutiny.

In September 2025, The Washington Post, citing satellite imagery and expert analysis, reported continued construction at the deeply buried site, suggesting that Iran may have been cautiously rebuilding activity there.

According to a Washington Post investigation based on satellite imagery and expert analysis, the site has remained under active construction even after last year's US and Israeli strikes on Iran's nuclear infrastructure.

Located roughly two kilometers south of the Natanz nuclear complex, the underground facility has been under excavation since 2020. Iran initially said it was building a new centrifuge assembly facility to replace one destroyed in what it described as an act of sabotage.

However, The Washington Post reported that the scale and depth of the tunnels have led some nuclear experts to speculate that the complex could instead serve as a covert uranium enrichment plant or a secure storage site for Iran's stockpile of highly enriched uranium.

The facility has never been inspected by the Atomic Energy Agency.

Experts cited by the newspaper said some underground chambers may lie between 260 and 330 feet below the surface, making them deeper than Iran's Fordow enrichment facility and potentially beyond the reach of existing US bunker-buster bombs.

Satellite imagery after the June US strikes showed signs of continuing activity, including expanded security walls, reinforced tunnel entrances, fresh piles of excavated earth and the presence of heavy construction equipment.

Analysts said these changes indicate that Iran may be continuing work underground while also strengthening the site against possible future airstrikes.

At the same time, the report said the construction does not necessarily show that Tehran is moving to build a nuclear weapon, and could instead reflect efforts to preserve or relocate sensitive nuclear activities after the attacks.

The fate of Iran's stockpile of uranium enriched to 60% purity also remains unclear, raising concerns among experts that the material could eventually be moved to an undisclosed underground facility such as Pickaxe Mountain.

- Ends