As soon as I saw the first news about it on Twitter, I guessed it was Iran that torpedoed the meeting, not O. Plain and simple: Which side can less afford to blow off the other at this point? Obama just backed down from a strike on Iran’s chief client in Damascus because he’s afraid to accept the political risk at home of an attack backfiring somehow when the public’s already war-weary. An attack on Iran would be waaaay riskier than an attack on Assad, and with Russia now offering to play pretend peacebroker between the U.S. and its enemies in the Middle East, diplomacy with Tehran is both more attractive and more politically possible for the White House than it’s been in ages. O would love to strike a sham deal on Iranian nukes a la Syria’s chemical weapons that lets him kinda sorta save face while avoiding a military attack, even if it ends up achieving little by way of actual disarmament. (Which is not to say that he’ll refuse to approve an Israeli attack on Iran, at least, if it comes to that.) That being so, of course Obama was eager to shake Rouhani’s hand. Of course he was.

In which case, if you’re Iran, with the president of the United States diminished and less of a military threat than he’s been in a long time, how do you resist a snub?

A potential encounter at the United Nations between U.S. President Barack Obama and Iranian President Hassan Rouhani failed to take place on Tuesday as the Iranians indicated it was too complicated, senior Obama administration officials said.

“There will be no meeting,” one official said.

The officials, who spoke on condition of anonymity, told reporters that Obama had been open to a meeting with Rouhani while both were in New York for U.N. activities but the Iranians were not ready to have an encounter at the presidential level.

So, once again, instead of keeping its cards close to the vest in order to minimize the risk of embarrassment if things go badly (see, e.g., the “red line”), the White House chatted up the possibility of an earth-shaking face-to-face between O and Khamenei’s new figurehead “president” and now has to explain why Iran didn’t feel like making it happen. Meanwhile, if you’re one of the people who’s excited about Rouhani’s alleged moderation, you’ve got two scenarios to grapple with here. Either (a) he’s not a moderate at all and made the decision to snub O himself or (b) he is a moderate but is so powerless within the regime that he can’t get away with so much as a handshake with Obama. As circumstantial evidence for the second theory (although it’s not inconsistent with the first), the Revolutionary Guard issued a statement on Sunday warning vaguely that Iran’s “diplomatic apparatus” should beware of White House officials. Maybe that was Rouhani’s cue to “rethink” any chummy gestures towards The One. Whatever his precise place in Iran’s hierarchy, it’s certainly below the IRGC’s.

On Twitter, Jeffrey Goldberg argues that the snub actually shows, er, Iran’s weakness, not Obama’s:

I.e. the snub exposes Iran’s hot air about negotiations for the blather it is, and now the U.S. and EU can huddle on more drastic action on nukes. Two problems with that, though. One: Why would anyone think this is Obama’s only shot at direct diplomacy? He’ll try again. The weakness of his position, as I described above, doesn’t change because Rouhani ducked him. In fact, Kerry is still set to meet with Iran’s foreign minister face-to-face at the UN later this week. That’s clever of the Iranians — embarrass O but keep stringing America along by increasing diplomacy in other ways. Two: Rouhani could communicate privately that he wanted to meet with Obama, whether that’s true or not, but that it was more reactionary elements in Iran like the IRGC that blocked him for now. That good cop/bad cop dynamic could be useful for Iran; they’re almost certainly practicing a version of it right now with all of Rouhani’s talk lately about moderation. Have him out front pleading with western diplomats that there are real moderate forces in Iran whom he represents, but in order to empower them the west needs to be even more patient with Iran and dedicated to diplomacy than it has been lately. And meanwhile Khamenei and the IRGC go about their bomb-building business.

Speaking of the glories of diplomacy, a Syrian defector tells David Ignatius that Assad has been busy lately moving his chemical weapons towards Iraq and Lebanon. Exit quotation from a Lebanese columnist: “[Assad] is also fortunate because there is an American president who has no appetite for war and because Russia wants to settle its scores with America (via Syria).”