"We believe that some aspects of the Western side are unjust and not in accordance with international legal norms," Russia's top negotiator Sergei Ryabkov said. "The model of a final resolution must be recognition of all Iranian rights included in the nuclear Non-Proliferation Treaty, including the right for enrichment."
The negotiations were "the most tense and intensive" yet and "there should be no pause in talks," Ryabkov said.
After the previous round of discussions in Almaty, six weeks ago, officials spoke optimistically about the prospect of a breakthrough. This time, the EU's Ashton said that while last week's talks got down to greater detail than before, "what matters at the end is substance."
She and Jalili have said they would talk with each other about a possible new round of negotiations after all the delegations have consulted with leaders in their capitals.
"The United States is far away from imposing the kind of massive pressure that could collapse the Iranian economy," according to analyst Mark Dubowitz, executive director of the Foundation for Defense of Democracies in Washington, who has been advising U.S. lawmakers on ways to tighten financial sanctions on Iran.
"In the absence of a diplomatic breakthrough or an internal development that shakes the regime, it is increasingly looking like Iran will either get the bomb or President Obama will order military strikes to forestall that possibility," Dubowitz said.
Thomas Pickering, former U.S. undersecretary of state, said his experience in negotiating with Iran suggests that it's premature to declare diplomacy dead.
"Expecting breakthroughs is over-optimistic," Pickering said in an interview. "These talks will be long and hard. But the progress is there," with "deeper engagement" in Almaty over a possible confidence-building deal.