The US military did not use bunker buster bombs on one of Iran’s largest nuclear sites last weekend, because it is so deep that the bombs likely would not have been effective, according to US Joint Chiefs of Staff Chairman Gen. Dan Caine, CNN reports.

Caine’s comment is the first known explanation given for why the US military did not use the Massive Ordnance Penetrator bomb against the Isfahan site in central Iran.

US officials believe Isfahan’s underground structures house nearly 60pc of Iran’s enriched uranium stockpile, which Iran would need in order to ever produce a nuclear weapon.

B-2 bombers dropped over a dozen bunker-buster bombs on Iran’s Fordow and Natanz nuclear sites. But Isfahan was only struck by Tomahawk missiles launched from a US submarine.

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