Obama and other US officials suggested Thursday they had received at least some indications that Iran was starting to take the kind of "concrete steps" they seek.
Tehran told officials at the talks it has accepted international inspections of a nuclear facility it only declared last week. In addition, Mr. Ahmadinejad suggested his country's openness to considering foreign-supplied fuel for Iran's nuclear reactors.
Open door to engagement?
Those two developments, along with the constructive demeanor of Thursday's talks, led US officials to conclude a door had opened to potentially fruitful engagement.
"It was a productive day but the proof of that has not yet come to fruition," Secretary of State Hillary Clinton told reporters in Washington after receiving a telephone report of the day from Assistant Secretary William Burns, the US representative at the one-day talks in Geneva.
"I will count it as a positive sign when it moves from gestures and engagements to actions and results," she added.
Going into Thursday's talks, the US had said it wanted Iran to accept "in weeks, not months" inspections of a nuclear facility near the holy city of Qom that the Iranians only declared last week. In his statement, Obama said the director of the International Atomic Energy Agency (IAEA), Mohamed ElBaradei, would visit Tehran in "coming days" to set up the inspections.
That may sound good, the ISIS's Albright says, but he notes that any delay allows Iran "to destroy evidence" and move installations to render inspections at least less useful. "So that's not a victory for the US at all," he says.