On Wednesday, a day after Iran agreed to hold nuclear talks with six world powers, an Iranian envoy said progress depends on the US demonstrating "genuine honesty and goodwill."
The talks, to take place in Kazakhstan on Feb. 26, are meant to help create a deal on Iran's nuclear development program. Iran says its nuclear ambitions are entirely energy-related, while The US, Israel and other western powers claim Tehran is seeking to develop nuclear arms.
"If they (the United States) demonstrate genuine goodwill and honesty, we'll have the best possible talks," Iran's envoy to Russia, Mahmoud Reza Sajjadi, said.
However, Sajjadi revealed doubts about the diplomatic effort.
"Our attitude to this proposal is positive ... but I ask you Russians, how much do you believe Americans?" Sajjadi said. "Obama said America would not let Israel build new settlements (in occupied territory) ... Did they keep their word?"
Previous diplomatic efforts have failed, and the US maintains tight financial sanctions against Iran.
President Obama has said he would not allow Iran to develop nuclear weapons.
According to The New York Times, "There is a general sense among experts that 2013 will be a make or break year for the negotiations."
On Tuesday, British Foreign Secretary William Hague said he welcomed a diplomatic solution. But, he added, "the need to make progress is increasingly urgent. Iran continues to enrich uranium in contravention of UN Security Council resolutions and on a scale that has no plausible civilian explanation."