Going nuclear Is Iran as close to building a weapon as Israel claims?

In justifying the attack on Iran, Israel's prime minister, Benjamin Netanyahu, said he had acted to pre-empt a secret Iranian programme to build a nuclear bomb, claiming Tehran already had the capacity to build nine nuclear weapons.

- Patrick Wintour

Israeli officials also claimed to have presented information to the US that Iran had recently made the necessary technical breakthroughs.

Netanyahu's critics are already saying he acted to pre-empt something else: a diplomatic agreement between the US and Iran on its civil nuclear programme, or even the demise of his own government. They point out Israel has warned that Iran is on the brink of building a bomb for 20 years.

Either way, Netanyahu's claim largely depends on Israel's formidable intelligence community possessing a greater state of knowledge about Iran's nuclear programme than either its US counterparts or the UN nuclear watchdog, the International Atomic Energy Agency (IAEA).

As recently as 25 March, Tulsi Gabbard, the US director of national intelligence, said the US intelligence community had assessed that Iran was not actively pursuing a nuclear weapon. However, Gabbard added that in past years, there had been "an erosion of a decades-long taboo in Iran on discussing nuclear weapons in public, likely emboldening nuclear weapons advocates within Iran's decision-making apparatus".

She added: "Iran's enriched uranium stockpile is at its highest levels and is unprecedented for a state without nuclear weapons."