US Secretary of State Mike Pompeo says a landmark nuclear deal with Iran was “built on lies”, after Israel claimed to have proof of a secret Iranian nuclear weapons programme.
He said it showed that the accord with Iran and six world powers in 2015 was based on deception, and not goodwill.
President Trump has long signalled his desire to abandon the deal and is due to make a decision in the coming weeks.
Other Western powers say Iran has kept to the deal and it should be continued.
Israeli Prime Minister Benjamin Netanyahu on Monday accused Iran of conducting a secret nuclear weapons programme, dubbed Project Amad, and said it had continued to pursue nuclear weapons knowledge after the project was shuttered in 2003.
That followed the revelation in 2002 by an exiled Iranian opposition group that Iran was constructing secret nuclear sites in breach of the nuclear Non-Proliferation Treaty, of which Iran was a signatory.
Mr Netanyahu presented what he said was evidence of thousands of “secret nuclear files” that showed Iran had lied about its nuclear ambitions before the landmark deal was signed in 2015.
Iran has always denied seeking nuclear weapons, and agreed three years ago to curb its nuclear energy programme in return for the lifting of sanctions.
The Israeli prime minister did not provide evidence that Iran had violated the accord since it went into effect in early 2016. But he insisted that Project Amad had continued at the Iranian defence ministry – citing the head of the programme as saying, “Special activities will be carried out under the title of scientific know-how developments.”
Iran’s Foreign Minister Javad Zarif said the move by Mr Netanyahu was a “childish” stunt to influence Mr Trump’s decision on whether the US should stick to a nuclear deal with Iran.
A spokesman for the UK government, a signatory of the deal, said it would continue to back the deal, adding: “We have never been naive about Iran and its nuclear intentions.”
Rob Malley, who was on the Iran negotiating team under the Barack Obama administration, played down the allegations, saying they were “nothing new”.
“The documents obtained by Israel from inside Iran show beyond any doubt that the Iranian regime was not telling the truth,” Mr Pompeo said in a statement.
“We assess that the documents we have reviewed are authentic,” he said, adding: “Iran hid a vast atomic archive from the world and from the International Atomic Energy Agency (IAEA) – until today.”
Mr Pompeo also warned that the US was now “assessing what the discovery of Iran’s secret nuclear files means for the future”.
Mr Trump, who has been vocal about his opposition to the Obama-era deal, said he had viewed part of Mr Netanyahu’s presentation and said the situation was “not acceptable”.
He said he would make a decision on whether to retain the deal on or before 12 May.