Donald Trump has confirmed the US has withdrawn from the Iran nuclear accord.
But how is this move likely to play out in the coming weeks and months?
:: The sanctions
Mr Trump said he will be reinstating the highest level of sanctions against Tehran. There will be a "wind down" period of 90 to 180 days – possibly longer in some circumstances.
White House national security adviser John Bolton said: "Some will extend to six months. Some might be 90 days. There might be other provisions as well."
:: What will Iran's President Hassan Rouhani do now?
Mr Rouhani has said Iran will remain committed to a multinational nuclear deal, despite the US pulling out. He has ordered his foreign ministry to negotiate with European countries, China and Russia in the coming weeks to keep the deal on the table.
:: Will Iran resume its nuclear activities?
Mr Rouhani has said Iran is ready to resume its nuclear programme after consultations with the other world powers. Under the nuclear accord, Iran said it had had curtailed its nuclear activities in return for the lifting of sanctions.
Mr Trump has maintained this did not happen, as has Israel's Prime Minister Benjamin Netanyahu.
:: What will the countries who were part of the deal do next?
The EU is determined to preserve the deal – and it wants to keep talks going in order to avoid escalation following Mr Trump's decision.
The leaders of the UK, Germany and France immediately urged the US not to take any actions that could prevent them and Iran from continuing to implement the agreement.
The statement from Prime Minister Theresa May, Chancellor Angela Merkel and President Emmanuel Macron also urged Iran to "show restraint" and continue fulfilling its own obligations such as cooperating with inspections.
:: What happens if the deal collapses completely?
If the deal collapses, Iran would be free to resume enrichment activities and businesses would have to act quickly to extricate themselves from all deals with Iran.
:: How will Mr Trump's decision affect Iran's economy?
Iran's economy is struggling and will be affected by US sanctions. Mr Trump especially wants to target its oil exports, and Iran's oil has already seen its value tumble as markets have been jittery for months over Mr Trump's impending decision.
:: Will Mr Trump renegotiate a new nuclear deal?
A new deal would have to satisfy so many issues the US has with Iran, such as its influence in Syria, Yemen, Iraq and Lebanon as well as its ballistic missile programme.
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:: Could the US launch a military strike on Iran?
If Iran – and it has stated it will – restarts its nuclear programme, there is a real possibility Mr Trump might be riled into launching military action. That is why the EU wants Iran to continue complying with the agreement.