A fourth round of indirect nuclear talks between Iran and the United States has concluded in the Omani capital, Muscat, with Iran’s Ministry of Foreign Affairs describing them as “difficult but useful”.

After about three hours of negotiations on Sunday, spokesman Esmaeil Baghaei described the talks as “difficult but useful talks to better understand each other’s positions and to find reasonable and realistic ways to address the differences”.

“Next round will be coordinated and announced by Oman,” he said in a post on X.

Before the talks started, Foreign Minister Abbas Araghchi told state media that Iran has a legal right to civilian enrichment of uranium that cannot be subjected to any deal.

Al Jazeera’s Tohid Asadi reports from Tehran.

Mark Pfeifle is a national security analyst and former deputy assistant to President George W. Bush.

He is also the president and founder of Off the Record Strategies. He joins me from Washington, DC to discuss the latest updates.