What is Pickaxe Mountain, Iran's underground nuclear facility Trump is threatening to attack?

The US president, Donald Trump, has again threatened to attack an Iranian nuclear site called Pickaxe Mountain. This comes as tensions between the US and Iran have increased recently.

While the current US military actions are focused on forcing Iran to reopen an important shipping route, Trump also stated his commitment to preventing Iran from developing nuclear weapons. He specifically mentioned Pickaxe Mountain, which is connected to Iran's nuclear program.

Pickaxe Mountain is a fortified underground site near Iran's main nuclear enrichment facility at Natanz. In Iran, it is known as Kuh-e Kolang Gaz La. Trump told reporters that the US military would soon attack the area heavily.

The facility is located about 220km south of Tehran and is very close to the Natanz nuclear site, which has been attacked before. Experts believe Pickaxe Mountain is still being built and is buried about 100 metres deep inside a mountain. It was not a target in previous US and Israeli attacks.

Construction at Pickaxe Mountain began in 2020, reportedly after an explosion caused by sabotage at the Natanz facility. Iran's nuclear chief at the time said the country was building a larger and more advanced facility inside the mountain to make special machines called centrifuges. These machines are used to enrich uranium, which is a key step in producing nuclear fuel.

The head of the International Atomic Energy Agency (IAEA) mentioned in March that Iran had planned to carry out nuclear activities at Pickaxe Mountain, stating that Iran systematically intended to place its sensitive facilities underground.

Satellite images show that the facility has entrances and a security wall. Recently, two tunnel entrances were reinforced to prevent vehicles from accessing them, though they are not completely blocked. These changes make it harder to target the site with powerful bombs designed to penetrate underground facilities.

Although Trump has threatened to attack Pickaxe Mountain, he also admitted that US intelligence sees no activity there currently. Experts believe the facility is not yet operational, and it is unclear when it might be ready. It is also uncertain if Iran still plans to build a large facility for making centrifuges there.

However, if Iran restarts its centrifuge production, it might build a smaller assembly facility at Pickaxe Mountain that could support a nuclear weapons program. Experts think the deep underground complex might be too difficult to reach with the most powerful US bombs. Aerial attacks also carry uncertainty regarding their effectiveness. Some reports suggest that past attacks on Iran's nuclear sites may have delayed its program by one to two years.

It's possible that the site could be attacked or sabotaged by ground forces, but other vulnerabilities might exist that could be exploited by deep earth penetrating weapons launched from the air. While ground operations have so far been avoided by Trump, the Iranians are taking steps to improve their defences at Pickaxe Mountain, showing they are concerned about potential attacks.