European diplomats say the latest round of talks over Iran’s nuclear program has made progress, expressing hope that agreement could soon be reached for Tehran to comply with a 2015 deal aimed at curbing its atomic ambitions and also see the United States rejoin the accord, AP reports.

Enrique Mora, the European Union official who chaired Wednesday's talks in Vienna, said delegations from Russia, China, Germany, France, Britain, Iran and the U.S. would return home to brief their governments and then meet again in the Austrian capital next week.

“I’m sure that the next round will be the one in which we will finally get the deal," Mora told reporters after the meeting.

Other European diplomats, speaking on condition of anonymity as they weren’t authorized to be quoted by name, described the talks in Vienna as “intense and productive,” but cautioned that they would become more difficult as delegates tackle harder issues.