French President Emmanuel Macron says he does not know whether US President Donad Trump will stick to the 2015 Iran nuclear deal.
Many in the West see it as the best hope of preventing Tehran from getting a nuclear bomb.
Trip to the US
Macron visited Washington last week in the hope of persuading Trump not to re-impose sanctions on Iran before a May 12 deadline, thereby imperilling the 2015 deal.
The French president said he had pushed the idea of a much broader Iran agreement with Trump, which was received "very positively".
However, the White House sounded unconvinced.
What does the agreement say?
Under the accord, Tehran agreed to limit its nuclear programme in return for relief from US and other economic sanctions.
The deal was struck by the UK, China, Frnace, Germany, Russia, the US and Iran.
What has the US said, then?
On Tuesday, White House press secretary Sarah Sanders said the agreement on limiting Iran's development of nuclear weapons was reached under false pretences. It claims the country's nuclear programme was more advanced than it indicated at the time.
What they are saying
"I don't know what the US president will decide on the 12th of May," Macron told reporters while on a visit to Australia. "I just want to say whatever the decision will be, we will have to prepare such a broader negotiation and a broader deal because I think no one wants a war in the region, and nobody wants an escalation in terms of tension in the region."