Via The Lede and Business Insider, which has an eye-popping graph showing what’s happening to the rial right now. We’ve all got debate fee-vah tonight but I want to put this on your radar screen in case things start to spiral in Tehran. The point of nuclear sanctions was to put Iran’s economy in a vise so that public discontent would force the regime to either back down on uranium enrichment or risk destabilization from within. Here’s a destabilizing tremor now:

Clashes and at least one spontaneous protest erupted in Tehran on Wednesday over the plunging value of Iran’s currency, as black-market money-changers fought with riot police who were dispatched to shut them down, and hundreds of angry citizens demonstrated near the capital’s sprawling merchant bazaar, where many shops had closed for the day. The official media reported an unspecified number of arrests including two Europeans.

The clashes were the first instance of a violent intervention over the money-changing business in Tehran since the currency, the rial, which had been gradually losing value in recent years, dropped drastically over the past week, losing 40 percent of its worth against the dollar, to a record low…

“They spend billions of dollars to keep Syrian President Bashar al-Assad in power, but now they say they have no money!,” one garment seller screamed as he was cheered on by others, witnesses reported. A team from Iran’s state television was nearly attacked when its reporter turned to the camera saying that the people behind him had been upset over a robbery.

Ahmadinejad’s been reduced to begging Iranians at press conferences not to convert their currency, which has lost four-fifths of its value this year, to something more stable. Israel, meanwhile, is sufficiently impressed that’s it veering away from the war track and towards calling for more sanctions. (Over the weekend, Israel’s finance minister claimed that Iran’s economy is on the verge of collapse.) One expert put it this way recently for WaPo:

“Two clocks are now running: a nuclear clock and regime-change clock,” said Clifford Kupchan, a former State Department official who now serves as a private consultant on the Middle East. “Sanctions have put a big hole in the revenue side of Iran’s budget, but the leadership doesn’t yet know that it’s on a cliff.”

“So are sanctions changing the nuclear program? No,” Kupchan said. “Are they buying time so the regime-change clock can run down? I’d say yes.”

Iran’s threatening to ramp up enrichment further if the current nuke talks fail, but they’re going to do that anyway. Question, then: How will Obama approach this if wider protests start breaking out and suddenly it looks like we’re in for 2009 redux? He’s taken tons of criticism, justifiably, for his passivity during the Green Revolution, but I don’t know if that necessarily means he’ll be more active during the next uprising. The Green Revolution was a backlash to Khamenei and the regime fixing the election for Ahmadinejad over Mousavi; the next uprising, if it comes, will be a backlash to hyperinflation that’s being driven by sanctions championed by … the United States. Considering that the nuke program is a source of Iranian national pride, how does Obama convince the public that it’s the regime’s stubborn refusal to give up the program that’s the cause of their misery rather than the west’s insistence on taking away their nuclear prerogative by strangling them economically? Maybe it doesn’t matter; if the regime falls, whatever replaces it will be desperate for economic relief and will have no choice but to play ball on nukes. Even so, it’s an odd position to be in diplomatically. And if we do reach the point where the regime faces extinction, it’s hard to believe that they won’t lash out somehow in major retaliation, either at Israel or at U.S. interests abroad or even right here. The next six months are going to be hairy.