Two weeks after the United States launched air strikes on three of Iran’s key nuclear sites, mounting evidence is puncturing President Donald Trump’s boasts that the facilities were “obliterated”.

From the head of the United Nations’ nuclear watchdog to leading American non-proliferation experts, scepticism is growing over Washington’s assertions that the strikes set back Tehran’s nuclear weapons ambitions “by years”.

Trump “appears to have already lost interest”, according to Barbara Slavin, a distinguished Middle East fellow at the Washington-based Stimson Centre think tank – apparently believing that a public declaration of victory renders negotiations with Iran unnecessary.

But nuclear experts agree: no one outside Iran can say with any certainty what has become of the country’s 900lb (409kg) stockpile of 60 per cent-enriched uranium. While this enrichment level falls one step short of weapons-grade, it is – by the UN’s reckoning – enough to produce as many as nine nuclear warheads were Tehran to take that final leap.

Instead of halting Iran’s progress, the US and Israeli attacks have triggered a retaliatory ban on International Atomic Energy Agency (IAEA) inspectors, cutting off the UN Security Council’s oversight of the country’s nuclear sites and, crucially, its cache of highly enriched uranium (HEU).

Before the strikes, the IAEA had what it described as a “comprehensive” picture of Iran’s HEU reserves and the centrifuges spinning to enrich uranium. But now, as Director General Rafael Grossi told US news network CBS last Sunday, “there is nothing”.

IAEA Director General Rafael Grossi said that before the US and Israeli strikes, the IAEA had detailed knowledge of the highly enriched uranium amounts and operational centrifuges needed for enrichment. Photo: Reuters

IAEA Director General Rafael Grossi said that before the US and Israeli strikes, the IAEA had detailed knowledge of the highly enriched uranium amounts and operational centrifuges needed for enrichment. Photo: Reuters