A second round of negotiations between Iran and the United States over Tehran’s rapidly advancing nuclear program ended Saturday after several hours of talks, Iranian and American officials said. There was no immediate readout on how the talks went at the Omani Embassy in Rome’s Camilluccia neighborhood.

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.

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.