Uranium enrichment inTehranwas the top negotiator on Sunday in new talks to revive the Iran nuclear deal in 2015.
``He's five minutes or he's five seconds to the finish line.
"Especially for Iranians and Americans, they are sensitive," Ulyanov said. "I can't give any guarantees, but my impression is that we are on the right track." said to be optimistic.
"We are making progress and hope to conclude negotiations soon," he told Iranian media.
Negotiators from Iran, the United States and the European Union resumed indirect talks on Tehran's battered nuclear deal on Thursday.
Since the agreement's de facto collapse, Iran has turned on advanced centrifuges and rapidly increased its stockpile of enriched uranium.
Iran signed a nuclear deal with the United States, France, Germany, the United Kingdom, Russia and China in 2015. Under the agreement, Iran agreed to limit its uranium enrichment under the watch of UN inspectors in exchange for the lifting of economic sanctions.
US President Donald Trump then said he would unilaterally pull the US out of the deal in 2018 and negotiate a stronger deal, but that never happened. . Iran began violating the terms of the deal a year later.
