These are the latest positive signals, which coincide with political dynamics inside Iran that consolidate Khamenei's position. Challenges from President Mahmoud Ahmadinejad last year have seen the fiery president sidelined. And parliamentary elections in early March were officially portrayed as a "victorious" vote of confidence in the regime.
This has enabled Khamenei to take charge of the nuclear dossier as never before, says a ranking former European diplomat who recently finished his tour in Tehran.
"Everything I hear in the last few months out of Iran is that it is Khamenei who is driving this this time, a difference [from] before, where he always had someone in between and different factions driving it," says the former diplomat, who asked not to be named.
Before the Istanbul talks in April, which broke a 15-month dry spell, Mr. Jalili was named a "personal representative" of Khamenei.
"That's clearly signaling [to the P5+1] that they are only dealing with one guy, which makes things much easier," says the former diplomat.
But while that may help streamline the nuclear negotiations, it is "not good" in the long-run for Iran's Islamic system, where past battles between competing power centers helped prevent a "normal dictatorship," he says.
"Now with everything concentrated on Khamenei, you have a bit more of the classical dictatorial structure, which also means that everything that goes wrong can only be attributed to one guy," adds the former diplomat.