A showdown looms at the United Nations on Tuesday as US President Donald Trump and Iranian leader Hassan Rouhani are set to square off during the world's biggest diplomatic gathering.
On the opening day of the General Assembly debate, Mr Trump and Mr Rouhani, Iranian President, will take their turn at the podium four months after the United States ditched a nuclear deal with Tehran.
The five remaining parties to the agreement – Britain, China, France, Germany and Russia – announced on Monday that they plan to keep business ties running with Iran, staring down Washington's move to impose sanctions.
Eyeing his second summit with North Korean leader Kim Jong-un, Mr Trump will tout his diplomacy with Pyongyang as a win, even though the North has taken little concrete action to dismantle its missile and nuclear programmes.
Mr Trump withdrew from the nuclear deal in May, to the dismay of European allies, Russia and China, which had invested years in negotiations to achieve a milestone agreement on keeping Iran's nuclear ambitions in check.
In his address, Mr Rouhani will stress that Iran continues to stick to the 2015 deal and will likely portray the US as a pariah for breaking its international commitments.
Mr Trump used his UN address last year to say the nuclear deal was "an embarrassment", signalling that the US was ready to walk away from the agreement.
After its exit, the US maintains it is seeking to ramp up pressure on Iran which it accuses of sowing chaos in Iraq, Syria, Yemen and Lebanon.
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"As I have said repeatedly, regime change in Iran is not the administration's policy," Mr Trump's national security adviser John Bolton said on Monday.
"We've imposed very stringent sanctions on Iran, more are coming, and what we expect from Iran is massive changes in their behaviour."
After a meeting on Monday, EU Foreign Policy Chief Federica Mogherini announced a new legal entity would be set up to preserve oil and other business links with Iran.
"This will mean that EU member-states will set up a legal entity to facilitate legitimate financial transactions with Iran and this will allow European companies to continue to trade with Iran," she told reporters, flanked by Iranian Foreign Minister Mohammad Javad Zarif.
Mr Rouhani said he has no plans to meet Mr Trump while in New York during the marathon of meetings. He has slammed a US offer of talks as "not genuine".
As a precondition for any dialogue, Mr Rouhani said the US president would need to repair the damage done by exiting the nuclear deal. "That bridge must be rebuilt," he told NBC news.
On Wednesday, Mr Trump will for the first time chair a meeting of the Security Council on non-proliferation that will give him a fresh opportunity to make the case for a tougher international stance on Iran.
"The Trump administration's approach toward Iran seems to boil down to: squeeze and let's see what will come," said Robert Malley, president of International Crisis Group.
"Rising tensions between the US and Iran in the absence of diplomatic channels is a recipe for an accidental, perilous clash."