Iran and the International Atomic Energy Agency (IAEA) agreed Saturday in Tehran on a path that could revive the country's 2015 nuclear deal, the UN agency and the country's government both said. 

The deal, known as the Joint Comprehensive Plan of Action (JCPOA), fell apart after former President Donald Trump pulled the US out of the agreement in 2018 and reimposed sweeping sanctions. 

What did Iran and the IAEA say? 

The president of Iran's Atomic Energy Organization, Mohammed Eslami, said on Saturday the two sides had concluded that "some documents which need to be exchanged between the IAEA and the Iranian organization should be exchanged" by May 22. 

Meanwhile, IAEA chief Rafael Grossi said the UN agency and Iran "did have a number of important matters that we needed... to resolve," but that they had now "decided to try a practical, pragmatic approach" to overcome them. 

Grossi for years has sought answers from Iran about man-made uranium particles found at former undeclared nuclear sites in the country. 

His trip to Tehran comes as parallel talks are taking place in Vienna, with the UK having indicated an agreement was close. 

The IAEA chief was optimistic about progress, but he warned that if open issues are not clarified, "it would be difficult to imagine you can have a cooperative relationship as if nothing had happened."

Grossi said he expected the clarification of open issues to conclude by June. 

Russia seeks 'guarantees' 

The next few days could mark a decisive point for negotiations on reviving the 2015 accord. 

Russia's Foreign Minister Sergey Lavrov weighed in on the issue, saying his country would seek guarantees from Washington before backing the nuclear deal.  

Moscow itself has been slapped with sanctions over its invasion of Ukraine, leading to high tensions between Russia and western nations. 

In particular, Lavrov said Russia had requested that the US provide written guarantees that Ukraine-related sanctions "will not in any way harm our rights to free, fully-fledged trade and economic and investment cooperation, military-technical cooperation with Iran." 

But the US was quick to dismiss the notion. "The new Russia-related sanctions are unrelated to the JCPOA and should not have any impact on its potential implementation," a US State Department spokesperson said. 

 "We continue to engage with Russia on a return to full implementation of the JCPOA. Russia shares a common interest in ensuring Iran never acquires a nuclear weapon," the spokesperson added. 

A senior Iranian official told Reuters news agency that Russia's demand is "not constructive" for talks between Tehran and global powers. 

jcg/wd (Reuters AP, AFP)