US President Donald Trump says he is extending sanctions relief for Iran one last time so Europe and the US can fix the nuclear deal’s “terrible flaws”.
The waiver he will sign suspends US sanctions on Iran for another 120 days.
The White House wants EU signatories to agree permanent restrictions on Iran’s uranium enrichment. Under the current deal they are set to expire in 2025.
Iran’s Foreign Minister Mohammad Javad Zarif said it was a “desperate attempt” to undermine a “solid” deal.
Germany said it would continue to call for the deal’s full implementation and would consult on a “common way forward” with the UK and France.
Mr Trump also wants Iran’s ballistic missile programme to be addressed.
“This is a last chance,” the US president said in a statement on Friday. “In the absence of such an agreement, the United States will not again waive sanctions in order to stay in the Iran nuclear deal.
“And if at any time I judge that such an agreement is not within reach, I will withdraw from the deal immediately.”
Also on Friday, the US imposed separate sanctions against 14 Iranian individuals and entities it accuses of rights abuses, censorship and support for weapons proliferators.
The US still maintains sanctions on Iran – independent of the nuclear deal – on matters such as terrorism, human rights and ballistic missile development.
What is the deal?
The landmark accord was signed between six global powers and Iran in 2015.
It saw Iran agree to reduce uranium enrichment activity drastically, dispose of its enriched uranium stocks and modify a heavy water facility so it could not produce material suitable for a nuclear bomb.
In return, decades of international and US nuclear-related sanctions were suspended, and the US president must sign a waiver suspending them every 120 days.
But Mr Trump has repeatedly criticised the deal – reached under his predecessor Barack Obama – as “the worst ever”.
What does the US want?
Senior Trump administration officials briefed reporters on Friday to say the president will work with European partners to broker an agreement limiting Iran’s ballistic missiles activities.
Mr Trump is prepared to back a modification to the existing deal if it was made permanent, one official said.
The president also wants the US Congress to amend a law on US participation in the nuclear deal, so that Washington could reimpose all sanctions if Iran breaches certain “trigger points”.
This will involve negotiations between the US and its European allies rather than talks with Iran, the official said.
BBC state department correspondent Barbara Plett Usher is sceptical that any international agreement can be negotiated in 120 days.
She says Iran is not interested in brokering a new deal, so Mr Trump will have either to back down or walk away.
Analysis by Jonathan Marcus, BBC diplomatic correspondent
Some four months ago when President Trump refused to re-certify the Iran deal he passed the baton to Congress while keeping the agreement in place.
This time he has put the ball in the Europeans’ court expecting Britain, France and Germany to come up with some accord that will, as he sees it, fix the deal’s shortcomings.
While they worry about Iran’s missile programmes and its regional activities, the Europeans believe the nuclear accord itself is working well. Furthermore even if they could come up with a follow-on agreement in a ludicrously short space of time, there is simply no chance of Iran agreeing to it.
So in another four months we will be back exactly where we are now. Mr Trump will have the problematic task of either re-imposing sanctions – effectively killing the nuclear accord – or of having to extricate himself from a problem of his own making.
Is the current deal working?
In October, President Trump refused to certify that Iran was in compliance with the accord, accusing the country of “not living up to the spirit” of the pact.
However, UN inspectors have certified nine times that Iran has not breached the deal.
European Union foreign policy chief Federica Mogherini, who helped broker the agreement, said on Thursday that the accord is “making the world safer”.
She said it was also “preventing a potential nuclear arms race in the region”.
What does Iran say?
Iran said on Friday that Mr Trump was “maliciously violating” the deal.
Foreign Minister Mohammad Javad Zarif said: “Trump’s policy & today’s announcement amount to desperate attempts to undermine a solid multilateral agreement.”
Tehran has vowed to stick to the accord as long as the other signatories respect it, but to “shred” it if Washington pulls out.
Iran says the missiles it has tested are not designed to carry nuclear warheads and insists its nuclear programme is a peaceful one for energy purposes.
What did the rest of the world say?
After Mr Trump’s announcement, Germany said it would “continue to campaign for the full implementation of the nuclear agreement”.
French President Emmanuel Macron phoned Mr Trump on Thursday to call for “the strict application of the deal and the importance of all the signatories to respect it”.
In Russia, Kremlin spokesman Dmitry Peskov said the pact was “the result of a consensus among many parties”.
The accord can be seen as “either good or bad, but it is the only one that reflects this consensus,” Mr Peskov said on Friday, ahead of Mr Trump’s announcement.