Technical experts from Iran, world powers and the UN atomic watchdog will start working out on Monday the nuts and bolts of implementing last month's landmark nuclear deal, reports AFP.
In particular, noted the news agency, the two-day Vienna meeting will seek to nail down the start date of Iran's promised six-month freeze of parts of its nuclear work, how this will be monitored and when sanctions will be eased.
After the talks with representatives from the United States, China, Russia, Britain, France and Germany, Iranian officials will then meet just with the International Atomic Energy Agency on Wednesday.
On November 24, Tehran committed to limit uranium enrichment to low levels for six months and not to make further advances at its Fordow, Natanz and Arak facilities.
Iran will also neutralize its stockpile of medium-enriched uranium and allow more intrusive IAEA inspections.
On Saturday, IAEA inspectors arrived in Iran for a visit to the Arak heavy water plant, the first such visit by inspectors in more than two years.
Iran's envoy to the IAEA, Reza Najafi, told reporters on November 29 that he expected the implementation of the deal to begin "either at the end of December or the beginning of January."
Iran's chief negotiator Abbas Araqchi said on Sunday that Iranian banking and sanctions experts would also be present at the Vienna meeting, one of several rounds he said would take place in the coming six months.
Under the deal, the P5+1 will release oil revenues frozen in bank accounts and ease some sanctions and trade restrictions in a package worth some seven billion dollars.
The core architecture of oil, finance and banking sanctions will however remain in place, resulting in lost oil revenues of $30 billion over the six months, according to the White House.
Israeli Prime Minister Binyamin Netanyahu has repeatedly said that the agreement that was signed with Iran is dangerous and will allow Tehran to continue its nuclear program and give nothing back to the West while being rewarded with sanctions relief.
This position has placed the Netanyahu at odds with the administration in the United States, to the point where President Barack Obama reportedly told him to “take a breather” from his criticism and shift attention to the terms of the final deal still under negotiation.
Both Obama and Secretary of State John Kerry defended the deal on Saturday as they spoke at the Saban Forum in Washington.
Obama said that the best way to prevent Iran from getting a nuclear weapon is “through a comprehensive, verifiable, diplomatic resolution," but stressed that all options remained on the table.
Kerry, who gave the keynote address at the forum several hours later, acknowledged that Iran with a nuclear weapons posed a "real" existential threat to Israel, but argued that the interim deal reached in Geneva would make Israel safer.
Netanyahu responded to Obama and Kerry in a speech of his own on Sunday, in which he said that stopping Iran's nuclear program is not enough and that Iran's policy of genocide must change, too.
He added the Jewish state shared Obama's "preference" to pursue diplomacy, "but for diplomacy to succeed, it must be coupled with powerful sanctions and a credible military threat."
"A diplomatic solution is better than a military option but a military option is necessary for diplomacy to succeed as a powerful sanction because of the pressure." Without the prospect of a military option, sanctions "will begin to unravel" in the wake of last month's deal, Netanyahu said via video link.