Leading article: Hostage to divisions in Iran

The case of the US-Iranian journalist sentenced by a Tehran court to eight years in prison for spying could thwart President Obama's best efforts to unfreeze relations with Iran. That almost goes without saying. Yet with the exception of the Tehran court, almost all parties to what could easily escalate into a diplomatic stand-off of the first order seem to be responding with an unusual degree of moderation. There may be more here than meets the eye.

The initial accusation against Roxana Saberi, a US citizen with an Iranian father and a Japanese mother, was that she had bought a bottle of wine – an illegal act in this Islamic country. This escalated in the course of two weeks into the charge of espionage that she eventually faced. While reprehensible, it is not unheard of for authoritarian governments to level unfounded spying charges against foreign reporters whose reporting they dislike. They are easy targets. And if, as it appears, Ms Saberi's permit had expired, she was vulnerable in a way she might not have been had her paperwork been in order.

The eight-year sentence passed by the Revolutionary court, however, seems out of all proportion, even by Iranian standards. And the country's President, Mahmoud Ahmadinejad, of all people seemed to agree. In a surprising intervention yesterday, he said that both Ms Saberi and Hossein Derakhshan, a Canadian-Iranian blogger imprisoned last November, must have the legal right to defend themselves and he called on prosecutors to ensure that their rights were not violated "even by an iota".

Mr Ahmedinejad's plea to prosecutors, made public by the official Iranian news agency, suggests that Mr Obama's overtures have split the Iranian leadership, and that Ms Saberi and Mr Derakhshan are effectively being held hostage to political in-fighting in Iran. If this is so, Washington's so-far measured response makes sense.

The coming days and weeks could be difficult, but the US should do nothing that would reinforce Tehran's suspicions of its motives. Some in the Iranian leadership may already have decided to spurn Mr Obama's extended hand, but there is now reason to hope that President Ahmedinejad is not one of them.