Hoping to use the positive momentum that was produced during the first round of discussions with Iranian negotiators, representatives of the five permanent members of the United Nations Security Council plus Germany initiated fresh talks with Tehran this weekend in Kazakhstan over the country’s nuclear program.

Friday’s negotiations are the first since February when both sides tried to narrow their differences over what would be an appropriate cap to Iran’s uranium enrichment efforts.

In contrast to three rounds of dialogue last year, when both sides refused to budge from their respective positions, this year’s diplomacy between Iran and world powers has taken on a more conciliatory tone. The maximalist position that the Security Council members took last year — Tehran was asked to stop all enrichment to 20 percent, ship that uranium out of the country and shut down the Fordow enrichment plant — has been discarded for a much more moderate proposal: Iran would receive a slight relaxation of economic sanctions in exchange for halting uranium enrichment at the 20 percent level.

The lead Iranian negotiator, Saeed Jalili, hailed the offer as a good first step and proof that the West was slowly coming to realize that it needs to make concessions in order to continue the process. Yet as much as the Iranians were pleased with the revisions, they did not formally respond to the offer.

A month has gone by and Tehran has had plenty of time to deliberate. The other parties expect the Iranians to officially respond with a counteroffer this weekend. If Iran continues to delay, it will signal that it is either unable to negotiate seriously or are unwilling to talk substantively about the matter.

The key question is whether world powers are prepared to accept Iran’s right to peaceful nuclear technology. Jalili has stated that the negotiations cannot go to the next stage without that assurance. Recognition of Iran’s right to enrich uranium will be essential for any comprehensive agreement but at this stage of the game, the six other nations, especially the United States, can hardly grant Iran that right unless it makes major concessions in return.