Representatives from five world powers met with Iranian officials in Vienna in an effort to revive the 2015 nuclear deal, which the United States abandoned in 2018.
Iran's chief nuclear negotiator, Abbas Araqchi, told state television that his April 6 talks with envoys from the remaining parties to the agreement -- Britain, China, France, Germany, and Russia -- were "constructive."
Russia's Vienna-based envoy to international organizations, Mikhail Ulyanov, said they got off to a 'successful' start.
The sides are expected to continue talks on April 9, with European diplomats acting as intermediaries facilitating indirect talks between U.S. and Iranian officials, whose delegations are staying in nearby hotels.
U.S. President Joe Biden has signaled his readiness to revive the accord abandoned by his predecessor, Donald Trump, but his administration says Iran must first return to its nuclear commitments. Iran has responded to the reimposition of crippling U.S. economic sanctions by gradually reducing its commitments under the deal, including increasing uranium stockpiles and levels of enrichment.
Iran says that the United States violated the deal by withdrawing and imposing sanctions, so Washington must act first.
"Lifting U.S. sanctions is the first and the most necessary action for reviving the deal,' Araghchi told state media. "Iran is fully ready to reverse its activities and return to complete implementation of the deal immediately after it is verified sanctions are lifted.'
Ahead of the talks, Washington predicted the meetings would be 'difficult' and steered clear of talk of a breakthrough, while Tehran insisted that it is 'neither optimistic nor pessimistic' and will not abandon its demand that U.S. sanctions be lifted before it acts.
After the April 6 talks, Ulyanov tweeted that two expert-level groups on sanctions lifting and nuclear issues were tasked 'to identify concrete measures to be taken by Washington and Tehran' to restore the deal.
The Russian envoy wrote in a separate tweet that it would take "some time" to restore the nuclear agreement.
'How long? Nobody knows. The most important thing after today's meeting of the Joint Commission is that practical work towards achieving this goal has started,' he wrote.
Earlier, Iranian media quoted Foreign Ministry spokesman Saeed Khatibzadeh as saying the other parties to the deal can negotiate with the United States but Iran won't engage in direct talks.
U.S. State Department spokesman Ned Price said on April 5 that the United States does not "underestimate the scale of the challenges ahead.'
"These are early days," Price said. "We don't anticipate an early or immediate breakthrough, as these discussions, we fully expect, will be difficult.'
Under the so-called Joint Comprehensive Plan Of Action (JCPOA), economic sanctions on Iran were eased in return for curbs on the country's nuclear program, which Tehran denies is for weapons development.
With reporting by Reuters, AFP, and dpa
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