A 15-tonne mega bomb is needed to destroy Iran's last nuclear facility – here's why Israel can't deliver it

Sky News AU

18-06-2025

Israel needs a 15-ton 'bunker buster' bomb to destroy the last untouched nuclear facility in Iran, but only the US has one.
Such a powerful weapon – the largest non-nuclear bomb in the US arsenal – is needed because the target, Fordow Fuel Enrichment Plant, is built some 300 feet inside a mountain near the city of Qom, two hours south of Tehran.
The heavyweight explosive is known as a GBU-57A/B Massive Ordnance Penetrator and was designed by Boeing for the United States Air Force.
Its huge weight means it can only be delivered with a B-2 Spirit stealth bomber – a jet Israel's air force does not possess.
'The United States controls the bomber and the bomb,' John Spencer, chair of urban warfare studies at the Modern War Institute at West Point military academy, told The Post. 'It would be an American plane and an American munition.'
The missile cost over $500 million for the US Army to develop, and was built to specifications which would allow it to penetrate deep enough into the Fordow plant to destroy the nuclear centrifuges in the complex, according to a 2013 article in the Wall Street Journal, which said at that time 20 of the bombs had been manufactured for the US military.
If the US does opt to help Israel with this extraordinarily powerful weapon, it will almost certainly turn the nuclear facility, protected by layers of granite and steel, to rubble.
'By weight and kinetic force, the GBU-57A/B Massive Ordnance Penetrator is designed to penetrate a certain amount of distance into the ground before it blows,' said Spencer.
'That's why these bunker busters are called Penetrators. They penetrate the ground before they explode. The explosion is strategically delayed.'
Although the US has sold less powerful bunker buster weapons to Israel, they have declined to share the Massive Ordnance Penetrator with any of its allies, partly to ensure it retains an upper hand, according to various reports.
As to what an explosion from a Massive Ordnance Penetrator would feel like, Spencer can only guess. 'I've seen 500 pounders, and they'll shake your teeth when they go off. It's like an earthquake. This will be much more than that.'
However, minimizing the likelihood of a nuclear explosion or leak, said Spencer, 'this [explosion] is pretty contained,' He explained that since the bunker buster explodes so far underground, under such strong armor, it is unlikely to cause a nuclear reaction. Instead of breaking through the surface, rubble would cave in. 'The risk is for leakage, not an explosion.'
US intelligence has long agreed Fordow is strategic to disabling the Iranian nuclear program.
'If you don't get Fordow, you haven't eliminated their ability to produce weapons-grade material,' Brett McGurk, who served as Middle East coordinator for several American presidents of both parties, recently told the New York Times.
In a less than ideal scenario, a state-of-the-art bunker buster is not the only solution.
It's also possible, said Spencer, that, without help from the US, Israel could do a jerry rigged attack on Fordow.
'Israel has cornered the market on what they call drilling,' said Spencer. 'They drop one bomb that reaches a certain depth, then another and another, at different angles, within seconds, to get to where they want to go. But you put multiple people and multiple aircraft at risk. The GBU is one and done.'
Considering that option, Spencer concluded, 'There are many ways to destroy the nuclear program in Iran. But this is the effective and efficient one. It gets to the objective quicker and is the perfect solution.'
Originally published as A 15-tonne mega bomb is needed to destroy Iran's last nuclear facility – here's why Israel can't deliver it