GENEVA — US and Iranian nuclear negotiators cited progress made but more work to be done at the conclusion of some of the highest level talks held between the two nations, involving four Cabinet secretaries and Iranian President Hassan Rouhani’s brother.

But in some ways, this low-key meeting at a hotel on the Geneva lakeside felt like a turning point in over a year of negotiations to reach a final nuclear accord that has already required two extensions. It was not so much in the typically cautious, much caveated language negotiators used to describe their progress, but in their body language that negotiators showed signs of growing confidence that they may be on track to reach a political agreement on major elements of a final nuclear accord in the coming weeks.

The talks here have allowed the parties “to very much sharpen up some tough issues so we can work to a resolution,” a senior US administration official, speaking not for attribution, told reporters at the conclusion of four days of talks here Feb. 23, which included not only Secretary of State John Kerry and Iran Foreign Minister Mohammad Javad Zarif, but also, for the first time, President of the Atomic Energy Organization of Iran Ali Akbar Salehi, and US Energy Secretary Ernest Moniz, as well as Rouhani’s brother, Hossein Fereydoun.

“These were very serious, useful and constructive discussions,” the US official said. “We have made some progress, but we still have a long way to go.”