The meeting comes almost three years after then-president Donald Trump pulled the US out of the Joint Comprehensive Plan of Action (JCPOA), also known as the Iran deal, after claiming that it had failed to reign in Tehran’s nuclear activity despite monitors saying it was complying.

“The US has so far failed to honor @POTUS [Joe Biden’s] campaign promise to rejoin the JCPOA. So this opportunity shouldn’t be wasted,” Iran’s envoy to the United Nations, Majid Takht-Ravanchi, said in a tweet posted before talks began.

The US is seeking to secure a full return to the original terms of the 2015 nuclear deal before any sanctions imposed under the previous presidential administration are removed. Meanwhile, Iran has called on Washington to lift all sanctions before Tehran comes to the negotiating table and meets with US officials.

Rob Malley, leading the US delegation, explained that these indirect talks are about “identifying the steps that the U.S. has to take and identifying the steps that Iran is going to have to take.”

Tehran and Washington have warned that the talks are expected to be challenging, as each has, so far, been unwilling to compromise on their position, with neither appearing to expect a result at the end of this meeting.

Other signatories of the 2015 agreement – China, France, Germany, Russia and the UK – are acting as intermediaries between Tehran and Washington. The European Union supported the deal, but has not attended the latest negotiations.