VIENNA — Nuclear talks were poised to intensify and go into overtime as a senior US negotiator suggested that all parties, but particularly the Iranians, may be experiencing some eleventh-hour jitters about the broader implications of concluding the nuclear accord they have all moved so far down the path to reach.

“We and the Iranians understand that this is a very important moment in the talks,” a senior US administration official, speaking on condition of anonymity, told journalists June 29. “It is certainly possible to get a deal here, and we do see a path forward to get an agreement that meets our bottom line. 

“But there are real and tough issues that remain which have to be resolved to get a comprehensive agreement, and we still don’t know yet whether we will be able to get there,” the US official said. “We want to, we hope, but we do not know.’’

Iranian Foreign Minister Mohammad Javad Zarif was expected to return to Vienna from consultations in Tehran on June 30, accompanied by Iranian atomic energy chief Ali Akbar Salehi, and Iranian President Hassan Rouhani’s brother, Hossein Fereydoun, an Iranian official told Al-Monitor on June 29.