Saeed Khatibzadeh told a weekly press conference that the talks have been difficult, but there is no "dead end" in Vienna. He said the talks need the US to make serious political decisions, and Tehran needs objective assurance that the US will not abandon the agreement again.

Iran is negotiating with Britain, France, Russia, China, Germany, and the US to revive the 2015 nuclear deal, formally known as the Joint Comprehensive Plan of Action (JCPOA), under which Iran will limit its nuclear program in return for the lifting of sanctions by the US and the West.

Iran signed the JCPOA with world powers in July 2015, but former US President Donald Trump pulled the US out of the agreement in May 2018 and reimposed unilateral sanctions on Iran, which prompted Iran to drop some of its nuclear commitments one year later and resume its halted nuclear programs.