Critical mass Is Iran as close to nuclear weapons as Netanyahu claims?

In justifying Israel's 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 bombs.

- 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 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 that Israel has been saying for 20 years that Iran is on the brink of building a bomb.

Either way, his 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, told the Senate intelligence committee that American intelligence had assessed that Iran was not actively pursuing a nuclear weapon.

However, Gabbard added that in the past years, there would appear to have 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".