While Mr. Obama did not rule out the possibility of engaging with Iran over the nuclear issue, administration officials and European diplomats say that the door to talks has all but closed, at least for now.

“I think that under these circumstances, no one is going to be able to pursue anything because there is nothing to pursue,” said Trita Parsi, the president of the National Iranian American Council, who has been consulting with White House officials “on a daily basis,” he said, about the unfolding situation in Iran.

Mr. Parsi said that all past assumptions about where Iran was headed had been cast aside by the disputed election results and the response of the protesters.

At some point confusion and hesitation has an impact of its own. The centrifuges are spinning, as they say, and there's only so much time for diplomacy before Iran has all the HEU it needs and there's nothing left to talk about. (Well, not exactly true: It's possible that Iran could develop plenty of bomb material but we could still convince them to stop short of building an actual weapon, a la Japan. Doesn't seem too likely, though.)

Hence this interregnum during which the US and our allies are trying to figure out what's really happening, and are reformulating our policies, plays nicely into the hands of Iran's nuclear hawks.

--Michael Crowley