Iran has declared it will no longer abide by any of the restrictions imposed by the 2015 nuclear deal.
In a statement it said it would no longer observe limitations on its capacity for enrichment, the level of enrichment, the stock of enriched material, or research and development.
The statement came after a meeting of the Iranian cabinet in Tehran.
Tensions have been high over the killing of Iranian General Qasem Soleimani by the US in Baghdad.
Two loud blasts were heard in the Iraqi capital on Sunday evening. Initial reports quoting witnesses say rockets landed near the US embassy there.
Hundreds of thousands turned out in Iran on Sunday to give Soleimani a hero’s welcome ahead of his funeral on Tuesday.
Under the 2015 accord, Iran agreed to limit its sensitive nuclear activities and allow in international inspectors in return for the lifting of crippling economic sanctions.
US President Donald Trump abandoned it in 2018, saying he wanted to force Iran to negotiate a new deal that would place indefinite curbs on its nuclear programme and also halt its development of ballistic missiles.
Iran refused and had since been gradually rolling back its commitments under the agreement.
Earlier on Sunday, Iraqi MPs passed a non-binding resolution calling for foreign troops to leave the country after the killing of Soleimani in a drone strike at Baghdad airport on Friday.
About 5,000 US soldiers are in Iraq as part of the international coalition against the Islamic State (IS) group.
The coalition paused operations against IS in Iraq just before Sunday’s vote.
The 2015 nuclear agreement with Iran, on life support ever since the Trump administration abandoned it in May 2018, may now be in its final death throes.
Donald Trump, throughout his presidential campaign and then as president, has never failed to rail against what he calls his predecessor President Barack Obama’s “bad deal”. But all of its other signatories – the UK, France, Russia, China, Germany and the EU – believe that it still has merit.
The agreement, known as the JCPOA, constrained Iran’s nuclear programme for a set period in a largely verifiable way but its greatest significance – even more so given the current crisis – is that it helped to avert an imminent war. Before its signature there was mounting concern about Tehran’s nuclear activities and every chance that Israel (or possibly Israel and the US in tandem) might attack Iran’s nuclear facilities.
Since the US withdrawal, Iran has successively been breaching some of the key constraints of the JCPOA. Now it appears to be throwing these constraints over altogether. What matters now is precisely what it decides to do. Will it up its level of uranium enrichment, for example, to 20%? This would reduce significantly the time it would take Tehran to obtain suitable material for a bomb. Will it continue to abide by enhanced international inspection measures?
We are now at the destination the Trump administration clearly hoped for in May 2018 but the major powers, while deeply unhappy about Iran’s breaches of the deal, are also shocked at the controversial decision by Mr Trump to kill the head of Iran’s Quds Force, a decision that has again brought the US and Iran to the brink of war.
What did Iran say?
A statement broadcast on state TV said the country would no longer respect any limits laid down in the 2015 deal.
“Iran will continue its nuclear enrichment with no limitations and based on its technical needs,” the statement said.
Enriched uranium can be used in nuclear weapons.
The statement did not, however, say that Iran was withdrawing from the agreement and it added that Iran would continue to co-operate with the UN’s nuclear watchdog, the IAEA.
The statement added that Iran was ready to return to its commitments once it enjoyed the benefits of the agreement.
Correspondents say this is a reference to its inability to sell oil and have access to its income under US sanctions.
Iran has always insisted that its nuclear programme is entirely peaceful.
Sanctions have caused Iran’s oil exports to collapse and the value of its currency to plummet, and sent its inflation rate soaring.
How has the international community reacted?
The other parties to the 2015 deal – the UK, France, Germany, China and Russia – tried to keep the agreement alive after the US withdrew in 2018.
EU foreign policy chief Josep Borrell has invited Iran’s Foreign Minister, Mohammad Javad Zarif, to visit Brussels to discuss both the nuclear deal and how to defuse the crisis over the Soleimani assassination.
German Chancellor Angela Merkel has agreed with French President Emmanuel Macron and UK Prime Minister Boris Johnson to work towards de-escalation in the Middle East, a German government spokesman was quoted as saying by AFP news agency.