The Iranian negotiating team has a difficult job in that they cannot currently disclose what they know so that they can avoid showing their hands to the rivals, Mousavi wrote in a tweet on Sunday.
He added that the Iranian experts knew that US returning to the 2015 nuclear deal without sanctions removal and guarantees not to repeat what happened in Donald Trump era would put Iran in a position even worse that the current situation.
Former US President Donald Trump ceased participation to the deal in 2018, resuming all sanctions lifted by the deal and adding many more sanctions with new labels.
Iran and the remaining parties to the deal, formally known as the Joint Comprehensive Plan of Action (JCPOA), are negotiating a possible return of the US to the deal.
Iran has demanded removal of all JCPOA-related sanctions and all the ones imposed during the Trump era.
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