US President Donald Trump has condemned Iran as a “fanatical regime” and refused to continue certifying an international nuclear deal.
He accused Iran of sponsoring terrorism and said he would deny the regime “all paths to a nuclear weapon”.
International observers say Iran has been in full compliance with the 2015 deal freezing its nuclear programme.
Iranian President Hassan Rouhani said the US was “more than ever isolated” and could not change the nuclear deal.
But Mr Trump said the deal was too lenient, and Iran had “committed multiple violations of the agreement”.
Iran, he said, was spreading “death, destruction and chaos”.
It was “not living up to spirit of the deal”, he said, but was receiving the benefit of sanctions relief regardless.
His new strategy would fix that, he said.
He said that the US reserved the right to leave the deal at any time, and in later remarks he said he would quit the deal unless “satisfactory” changes were made.
Mr Trump had been under pressure at home and abroad not to scrap the deal between Iran and the US, UK, France, China and Russia plus Germany.
How did key players respond?
Within minutes of his address, EU’s foreign policy chief Federica Mogherini insisted the deal was “robust” and that there had been “no violations of any of the commitments in the agreement”.
She said it was not in the power of “any president in the world” to terminate the agreement, which had been established by a UN Security Council resolution.
In a joint statement, the UK, Germany and France said they were “concerned” by Mr Trump’s move but remained committed to the deal. But they added they also “shared concerns about Iran’s ballistic missile programme and regional activities”.
Russia’s foreign ministry said it believed Mr Trump’s stance did not correspond to the spirit of the deal and insisted Iran was compliant, reported Reuters news agency.
Israeli Prime Minister Benjamin Netanyahu congratulated Mr Trump, who he said had “boldly confronted Iran’s terrorist regime”.
What violations of the nuclear deal did Mr Trump say Iran had committed?
On two occasions, he said, they had exceeded the limit of 130 tonnes of heavy water (a source of plutonium suitable for a nuclear bomb) .
Until recently, he said, the regime had failed to meet expectations in its operation of advanced centrifuges.
He claimed it had also “intimidated international inspectors into not using the full inspection authorities that the agreement calls for”.
What does the Trump administration want to change about the deal?
Among the changes it is seeking is the end to the “sunset” clauses in the deal, one of which sees restrictions on Iran’s nuclear enrichment programme lifted after 2025, greater access to nuclear sites and the inclusion of Iran’s ballistic missile programme.
What steps is it taking outside the deal?
Mr Trump focused on the activities of the Revolutionary Guards, which he called the “corrupt personal terror force of Iran’s leader”, and Iran’s missile programme, which he said threatened “global trade and freedom of navigation”.
A key criticism of the Iran deal by Mr Trump has been that it fails to cover Iran’s ballistic missile programme. Last month, Iran successfully tested a new medium-range missile with a 2,000km (1,200-mile) range.
Mr Trump said he would impose sanctions outside the Iran deal targeting both.
Why is Trump speaking now?
Under the Iran Nuclear Agreement Review Act (Ingra), Congress requires the US president to certify every 90 days that Iran is upholding its part of the nuclear agreement.
Mr Trump had already recertified it twice and had a deadline of Sunday to make his latest report back.
But his refusal to recertify gives Congress 60 days to decide whether to pull out of the nuclear deal by re-imposing sanctions.
What is the background to this tougher stance?
A strategy paper released by the White House highlights calls for neutralising Iran’s “destabilising influence and constraining its aggression, particularly its support for terrorism and militants”.
The US, it says, will work to revitalise traditional alliances and regional partnerships as “bulwarks against Iranian subversion”.
Efforts will be made to deny funding for the Iranian government and the Revolutionary Guards’ “malign activities” and counter threats from ballistic missiles “and other asymmetric weapons”.
What is the nuclear deal?
Formally known as the Joint Comprehensive Plan of Action, it is designed to prevent Iran developing a nuclear weapon.
It lifted some sanctions that stopped Iran from trading on international markets and selling oil.
The lifting of sanctions is dependent on Iran restricting its nuclear programme. It must curb its uranium stockpile, build no more heavy-water reactors for 15 years and allow inspectors into the country.