Mr. Trump’s chief envoy to the talks, Steve Witkoff, has also sent mixed signals over what the United States wants. Over the past week, he has moved from suggesting Iran could have a limited nuclear program to saying Iran needed to fully dismantle it.

Israel has not ruled out an attack on Iran's nuclear facilities in the coming months despite President Donald Trump telling Israeli Prime Minister Benjamin Netanyahu that the U.S. was for now unwilling to support such a move,

The United States and Iran are due to hold their second round of nuclear talks on Saturday, as what both sides are looking for in a deal begins to take shape.