Donald Trump is planning to abandon the Iran deal on the basis that it is not in the national interest, according to US media reports.
Although he has not confirmed what his intentions are, at a meeting of military leaders at the White House yesterday Trump warned that attendees were experiencing "the calm before the storm" - but would not be drawn further by reporters present, saying only: "You'll find out."
We've got the answers to some of the questions you might have:
What is the Iran deal?
The Iran deal is an accord struck in 2015 after nine years of negotiations aimed at curtailing the Middle Eastern state's nuclear weapons-building capacity, in exchange for the lifting of a range of economic sanctions imposed by the West. Sanctions were first applied to Iran in 1979, after the storming of the US embassy, and heavily restricted the country's access to international markets and, in particular, its ability to sell oil.
As well as the US, France, Germany, China, Russia and the UK are partners in the deal.
Didn't Trump already give this plan the go ahead?
He did. Despite slamming the agreement during his campaign, Trump certified that Iran was holding up its end of the bargain in April and July. The deal must be certified every 90 days.
However, the president is now expected to "decertify" the accord and declare that it is not in the national interest.
Trump said this week that Iran has "not lived up to the spirit of their agreement".
"The Iranian regime supports terrorism and exports violence and chaos across the Middle East," he added.
That is why we must put an end to Iran's continued aggression and nuclear ambitions. You will be hearing about Iran very shortly.
So what happens next?
If Trump rejects the deal this time around, Congress has 60 days to decide whether or not it will impose sanctions on Iran. According to US media, the deal will probably be left in place.
However, even if Congress does go with this option, experts have warned that the President may have sparked a gradual breakdown of the accord. "This approach could kill the agreement by a thousand cuts," Kelsey Davenport of the Arms Control Association told CNN.
What happens if the deal is scrapped?
Critics have warned that Trump is putting US national security at risk by entertaining the possibility of re-imposing sanctions on Iran.
Meanwhile, Trump is also putting relations with his European allies at risk. Both Theresa May and France's Emmanual Macron have recently tried to persuade their US counterpart to continue supporting the deal, apparently to no avail.
"What would happen if the agreement collapsed? The truth is that Iran — not the United States or Britain — would regain the most freedom of action. Without the constraints on their nuclear program, Iran’s leaders could bring back the centrifuges and rebuild the uranium stockpile," the foreign secretary wrote in a Washington Post article this summer.
What options would the United States and Britain gain? In theory, we could reassess sanctions, but in the meantime we would face all the perils of Iran rebuilding its nuclear program.