Iran will produce 60%-enriched uranium in retaliation for a suspected Israeli attack on a nuclear site, President Hassan Rouhani says, bringing it closer to the purity required for a weapon.
The three countries are parties to a 2015 nuclear deal with Iran, under which it is permitted to enrich uranium up to 3.67% purity to make reactor fuel.
Israel, which sees Iran's nuclear programme as a potential threat to its existence and is critical of Joe Biden's efforts to revive the deal, has neither confirmed nor denied involvement in the Natanz incident.
US intelligence officials told the New York Times that a large explosion completely destroyed the power system that supplied an underground hall at Natanz where uranium hexafluoride gas was fed into centrifuges to separate out the most suitable isotope for nuclear fission, called U-235.
On Tuesday night, Iran's ambassador to the International Atomic Energy Agency (IAEA) announced it had just started enriching uranium up to 60% purity for the first time in response to the attack.
Mr Rouhani said those responsible wanted to derail the indirect talks between US and Iranian officials in Vienna which are aimed at reviving the nuclear deal, formally known as the Joint Comprehensive Plan of Action (JCPOA).
The governments of France, Germany and the UK said enriching uranium up to 60% was "a serious development" since it constituted "an important step in the production of a nuclear weapon".
In their annual threat assessment released on Tuesday, US intelligence agencies said they continued to "assess that Iran is not currently undertaking the key nuclear weapons-development activities that we judge would be necessary to produce a nuclear device"?
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