Leaders from the United States and Iran painted a positive but cautious picture of talks between the nations over Iran’s nuclear program Saturday, after the third phase of the discussions wrapped up in Oman.

Washington opposes Tehran’s insistence on retaining the ability to enrich uranium, but U.S. calls latest round “productive.”

The US and Iran reported signs of progress in talks on a deal over Iran’s nuclear program after what the Iranian foreign minister described as increasingly detailed discussions.