Iran and the United States concluded a fifth round of high-stakes nuclear talks in Rome on Friday amid growing skepticism in Tehran about the chances of a deal as Washington hardens its position.

Iran and the U.S. have see-sawed between enmity and grudging diplomacy in the years since, with relations peaking when Tehran made the 2015 nuclear deal with world powers. But Trump unilaterally withdrew America from the accord in 2018, sparking tensions in the Mideast that persist today.

Iran said it’s “time to decide” ahead of Friday’s nuclear talks with the US, with the main sticking point being whether Tehran will be able to continue enriching uranium.