It's been an article of faith for nearly a decade that Iran's supreme leader issued a fatwa — a religious edict — that nuclear weapons are a sin and Iran has no intention of acquiring them.
President Obama and Secretary of State Hillary Clinton recently made references to this religious commitment from Iran's leader, Ayatollah Ali Khamenei.
But with the next round of nuclear talks scheduled to resume on Monday in Moscow, analysts point out that there are serious questions about the nature of the fatwa and whether it's as persuasive as the Iranians would like the world to think.
As far as anyone knows, the fatwa was never written down.
The first time Khamenei proclaimed that nuclear weapons were un-Islamic was in 2003. He has repeated this numerous times since them, notes Muhammad Sahimi, who writes for the website Tehran Bureau.
"Khamenei has been consistently saying at least for the past seven or eight years that the production of nuclear weapons is against Islamic teaching and therefore Iran will never pursue such a path," Sahimi says