Nuclear talks between Iran and the 5+1 ended in Geneva today, Sunday November 10, falling short of a final deal.

Catherine Ashton, the EU foreign policy chief, said that despite “concrete progress… some differences remain.”

Ashton went on to report that the talks would resume on November 20.

Iranian Foreign Minister Mohammad Javad Zarif told the press conference that he was optimistic about the talks, which he said were “something to build on.” Zarif added that since all parties were “on the same wavelength… there was the impetus to reach an agreement.”

The U.S. foreign secretary also expressed optimism about the talks, saying: “There is no question in my mind that we are closer now than we were before.”

“We have not only narrowed differences and clarified those that remain,” John Kerry said; “but we made significant progress in working through the approaches to this question of how one reins in a program and guarantees its peaceful nature."

Kerry qualified his statement by saying that the window for diplomacy will not remain open indefinitely.

Iranian President Hassan Rohani called on world powers not to miss out on an “exceptional opportunity” to finalize a deal.

British Foreign Secretary William Hague also called on negotiators to “seize the moment.”

The French foreign mnister Laurent Fabius appears to have presented a tougher stance at the last moment pre-empting a possible deal.