Vienna — The secret US-Iran diplomatic channel that helped advance the interim nuclear deal last year got underway after a message from US President Barack Obama was conveyed to Iran: The United States would be prepared to accept a limited Iranian domestic enrichment program as part of a nuclear agreement in which Iran would take concrete and verifiable steps to assure the world its nuclear program would remain exclusively peaceful.

“Basically it was to inform Iran that we are prepared to accept a limited enrichment program in the context of an otherwise acceptable deal,” former US-Iran negotiator Robert Einhorn told Al-Monitor in an interview July 13. “It was not a specific quid pro quo.”

Now, as negotiators from Iran and the six world powers (P5+1) pursue marathon nuclear talks here to try to reach a final nuclear accord by the July 20 deadline when the interim deal expires, the United States believes that US concession, and the successful interim deal it helped bring about, should help persuade Iran to significantly delay, if not abandon, its desire for a large-scale enrichment program for the sake of reaching a comprehensive nuclear accord.

“I think that the United States has already made a number of very tough choices," a senior US administration official, speaking not for attribution, told journalists at a briefing in Vienna July 12. In the six-month interim Iran nuclear deal, the Joint Plan of Action (JPOA), "the President of the United States took, I think, a very bold decision to say that we would be open to discussing a very limited enrichment program to meet the practical needs of Iran.”