The site at Pickaxe Mountain may have been chosen to protect it from air strikes with some analysts estimating, external the core of the facility could be roughly 100m (328ft) underground.

This would also mean it’s buried deeper than Iran’s two nuclear enrichment complexes at Fordo and Natanz which the US bombed last year using what are known as bunker buster bombs – the only known weapon that could conceivably reach such concealed sites.

The US GBU-57 bomb weighs about 13,000kg (30,000lb) and is reported to be able to penetrate 18m (60ft) of concrete or 61m (200ft) of earth before exploding.

But even using these munitions, experts say the US would be unlikely to completely destroy Pickaxe Mountain.

“Obliterating every underground chamber would be extremely difficult because of the facility’s depth and uncertain layout,” says Arman Mahmoudian, a research fellow specialising in Iran at the University of South Florida.

However, the US could target tunnel entrances, communications systems, access roads, and other supporting infrastructure, Mahmoudian adds, which “could paralyse the facility’s operations even if some of its deepest underground sections survived”.

Meanwhile, Faragasso says the site may be potentially vulnerable and that “targeting the ventilation shafts would enable the weapons to reach deeper into the facility, and the tunnel portals can be collapsed using bunker buster weapons”.