Iran’s top negotiator to the nuclear talks in Vienna, Abbas Araqchi, says despite progress made on some key differences, he is still not confident a conclusion is possible. Iran and the remaining signatories of the nuclear deal, the Joint Comprehensive Plan of Action, the JCPOA , have been engaged in talks to revive the deal since April, entering into a fifth round of talks aimed at the removal of US sanctions and a return to full compliance by Iran.

Iranian lead delegate Deputy Foreign Minister Abbas Araghchi said the difficult issues that still need to be resolved have become less although decisions must be made on the remaining differences.

Iran has been demanding the removal of all US sanctions including those imposed under other labels against individuals and entities under the former administration of Donald Trump. Iran has also made it clear it will only come back to full compliance after it has verified the effective removal of sanctions; demands, that up until now have not been met.

Araghchi says he’s seen determination and seriousness by all parties involved to reach a conclusion in the coming days, a prospect that he admits, is still not by any means certain.