Riyadh, Jan 16 : Chief negotiators of Iran and three European countries have temporarily returned to their home countries for consultations as expert talks continue, providing the latest evidence that international talks to salvage the 2015 nuclear deal in Vienna have been moving forward. The return of chief negotiators to their countries does not mean the eighth round of talks has stopped, according to the website of Iran's Foreign Ministry. The eighth round of negotiations between Iran and other remaining signatories to the Joint Comprehensive Plan of Action (JCPOA) began on December 27, 2021 with the US indirectly involved after its pullout in 2018 from the landmark pact, reports Xinhua news agency. "There's a better atmosphere since Christmas," European Union (EU) foreign policy chief Josep Borrell told reporters following an informal meeting of EU foreign ministers in the French city of Brest. "Before Christmas, I was very pessimistic," he said, adding that "today I believe reaching an accord is possible", even within the coming weeks. Meanwhile, there is "real progress" on the restoration of the JCPOA, Russian Foreign Minister Sergey Lavrov said. "There is real progress there, there is a real desire, first of all between Iran and the United States, to understand specific concerns, to understand how these concerns can be taken into account in a common package," Lavrov told a press conference. The Vienna talks are "moving forward on right track", Iran's official IRNA News Agency reported on Saturday. "The number of issues of difference has decreased and delegations are busy to discuss the way of implementing any potential agreement," the report said, quoting an informed source on condition of anonymity. Also, Mikhail Ulyanov, head of Russia's delegation to the nuclear negotiations, said that the diplomats in Vienna primarily paid attention to "to (the) implementation of a future deal". "We need to agree on who will be doing what and when on the way towards full restoration of the nuclear deal," which is not an easy task, he added. Though in a positive atmosphere, it's reported that a wide range of issues remains unresolved in the nuclear talks, given Iran and the US, the two main parties, indirectly exchanging messages. "We are discussing difficult issues and considering the ways to prepare the draft of the agreed principles," Iran's Mehr News Agency reported on Saturday, citing a source close to the Vienna talks. According to the reports, about the removal of the sanctions and nuclear issues, lots of disputes have been resolved, and the negotiators "are increasingly working on the third appendix on how to implement and sequence the possible agreement". The informed source noted that this phase of negotiation is "one of the most tedious, time-consuming and difficult parts of the negotiation, but it is indispensable to achieve the goal". While the diplomatic endeavorus are going on, Washington still carries on with its pressure campaign. There are only "a few weeks left to see if we can get back to mutual compliance", US Secretary of State Antony Blinken said last week, warning his country stands ready to look at "other options" if negotiations fail. However, Tehran has repeatedly vowed that it will not make hasty concessions under pressure. /IANS