A landmark deal in 2015, formally known as the Joint Comprehensive Plan of Action (JCPOA), gave Iran sanctions relief in exchange for curbs on its nuclear program to guarantee that Tehran could not develop a nuclear weapon -- something it has always denied wanting to do.
Iran’s chief nuclear negotiator returns to Vienna
Iran's chief negotiator will fly back to Vienna on Sunday evening following consultations in Tehran, state media reported, as talks to revive the 2015 nuclear deal reached a critical stage.
