Formal talks in Vienna on reviving Iran’s 2015 nuclear agreement with world powers are set to continue Friday [April 9] with a meeting of the remaining parties to the JCPOA (Joint Comprehensive Plan of Action) due to hear input from two expert groups set up on Tuesday.

Such input appears to be a first stage in a longer process. The United States spokesman Ned Price said in Washington that the expert-level talks “may resume in the coming days, potentially next week,” with Rob Malley, the US special envoy on Iran, returning to Washington before the weekend. Malley, while not involved in the formal talks of JCPOA members, has been in indirect contact from a separate hotel.

The expert-level groups have been examining measures to revive the JCPOA, which the US left in 2018. This boils down to which United States sanctions should be lifted as incompatible with the agreement, and which of the post-2019 steps in Iran’s nuclear program should be reversed to bring it back in line with the deal.

But this involves complexities. Some steps taken by Iran, especially in research and development, are now perhaps irreversible, while the Trump administration in its final weeks levied sanctions on Iran, ostensibly unrelated to nuclear program, that it openly said would complicate efforts by a Biden administration to revive the agreement.

Hence the reference this week from Iran’s foreign ministry spokesperson Saeed Khatibzadeh to "all imposed, re-imposed and re-labeled sanctions." Hence also Price’s comment on Wednesday that while the US was prepared to lift sanctions inconsistent with the JCPOA, he could not offer "chapter and verse on what those might be."

Meanwhile, Congressional Republicans sent a letter to Secretary of State Antony Blinken Wednesday informing him that they will not be bound to any agreement with Iran that would grant relief from economic sanctions, The Washington Free Beacon reported. This would be a signal to Tehran that even if it reaches agreement with the Biden Administration, a future Republican president can abandon it just as Donald Trump did with the JCPOA that was not ratified by Congress.

A tweet on Thursday afternoon  from Rafael Mariano Grossi, head of the International Atomic Energy Agency (IAEA), hinted at progress. Grossi noted that he and Araghchi, leading the Iranian delegation, had conducted a “thorough exchange” on “current consultations and ongoing bilateral activities” as the IAEA continued “its professional technical verification and monitoring in Iran…”

But Grossi has stressed since December, even before President Joe Biden took office wanting to return the US to the JCPOA, that reviving the deal was a challenge that required a plan agreed by the politicians for sequencing steps by the US and Iran, which the IAEA could then monitor.

Adding to other complexities Iran has refused face-to-face talks with the American until the US returns to the JCPOA, meaning the US delegation in Vienna, led by Malley, has been effectively dealing with the Iranian delegation indirectly, reportedly though the French.