More than 40 former European officials have called on both the US and Iranian leadership to successfully complete the negotiations to revive the nuclear deal.

The open letter published on Tuesday is led by the International Crisis Group, which is a Brussels-based transnational non-profit think tank consisting of policymakers and academics that describes itself as "working to prevent wars and shape policies that will build a more peaceful world".

The letter, signed by members of the European Leadership Network, board members of the group and council members from the European Council on Foreign Relations, said that the parties to the Vienna nuclear talks are now within touching distance of reinstating the Joint Comprehensive Plan of Action (JCPOA).

Expressing their growing concern over the fate of the talks, they said a period of stasis in the talks threatens to undo the progress made in recent months “toward reinstating a non-proliferation achievement that is crucial for international peace and security.”

“At a time when transatlantic cooperation has become all the more critical to respond against Russia’s unprovoked invasion of Ukraine, for U.S. and European leaders to let slip the opportunity to defuse a nuclear crisis in the Middle East would be a grave mistake”, read the letter.

The US and the Islamic Republic have held more than one year of talks to revive the JCPOA, but the diplomatic process is at a standstill since March. Iran is demanding the removal of its Revolutionary Guard from the US list of terrorist organizations, something the administration has so far not accepted.