That the talks are even happening represents a historic moment, given the decades of enmity between the two countries since the 1979 Islamic Revolution and the U.S. Embassy hostage crisis.

A second round of nuclear talks between the United States and Iran is underway, as what both sides are looking for in a deal begins to take shape. Delegations from both countries met in Oman last weekend for talks mediated by the Gulf Arab nation.

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.