The US and Israeli bombing of Iranian nuclear sites creates a conundrum for UN inspectors in Iran: how can you tell if enriched uranium stocks, some of them near weapons grade, were buried beneath the rubble or secretly hidden away?

Following last weekend's attacks on three of Iran's top nuclear sites - at Fordow, Natanz and Isfahan - President Donald Trump said the facilities had been "obliterated" by US munitions, including bunker-busting bombs, Reuters reported.

But the UN nuclear watchdog, the International Atomic Energy Agency, which monitors Tehran's nuclear program, has said it's unclear exactly what damage was sustained at Fordow, a plant buried deep inside a mountain that produced the bulk of Iran's most highly enriched uranium.