One thing I heard over and over again during my visit to Tehran in June was that the two sides in Iran’s political divide were intent on sabotaging any US-Iran deal concluded by the other side. If President Ahmadinejad moves toward an agreement with the West over Iran’s nuclear program, anaylsts told me, the centrist-reformist opposition would denounce it and work to unravel it. On the other hand, if former Prime Minister Mir Hossein Mousavi won the election, reformists told me, he would move toward exactly such a deal — and the right-wing, including Ahmadinejad, would howl and oppose it.

Well, Ahmadinejad won, Mousavi lost — at least, that’s how the story goes — and voila! the prediction has come true. Ahmadinejad wants a deal, and Mousavi is trying to wreck it.

Yesterday, on his web site, Mousavi issued a militant criticism of Ahmadinejad’s diplomacy. Mousavi bitterly denounced the plan, supported by Ahmadinejad, to ship the bulk of Iran’s enriched uranium to Russia and France for use in fabricating fuel for a medical-use reactor. That accord, announced October 1, in the first US-Iran talks in thirty years, was widely seen as a breakthrough. But Mousavi is having none of it. He said:

“The discussions in Geneva were really surprising and if the promises given (to the West) are realised then the hard work of thousands of scientists would be ruined.”

Meanwhile, Ahmadinejad is sounding like a dove:

“As long as this government is in power, it will not retreat one iota on the undeniable rights of the Iranian nation. Fortunately, the conditions for international nuclear cooperation have been met. We are currently moving in the right direction and we have no fear of legal cooperation, under which all of Iran’s national rights will be preserved, and we will continue our work.”

Still, Iranian officials told the US and the P5 + 1 that it is having second thoughts about the agreement. According to various media accounts, Iran’s negotiators have said that they will not ship out the bulk of the enriched uranium — instead, they will dispatch batches of fuel, piecemeal, as they refine additional uranium. Under such a plan, Iran will retain a stockpile of low-enriched uranium that is enough, analysts say, to manufacture a single bomb. (That, of course, would require Iran to further enrich its low-enriched uranium to weapons grade, a very time-consuming and laborious process.)

In many ways, it isn’t surprising the Mousavi would emerge as a staunch defender of Iran’s nuclear program. In the early 1980s, it was Mousavi and former President Ali Akbar Hashemi Rafsanjani, his current backer and ally, who teamed to oppose a decision by then-Leader Ayatollah Khomeini to end the nuclear program that began under the Shah. But Mousavi’s opposition to Ahmadinejad’s deal is pure political opportunism. He is using the nuclear issue as part of his all-out war against Ahmadinejad’s rule. It is just one example of the radioactive nature of nuclear politics in Iran — and it reveals why the talks between Iran and the P5 + 1 will be difficult and complex.

That’s precisely why bluster, threats and sanctions are a bad idea. The talks are going to take a long time. In the end, they may or may not succeed. Stripped of the political back-and-forth, the fact of the matter is that nearly all sides in Iran would like a deal that protects Iran’s basic right to enrich uranium, for peaceful purposes, under appropriate international supervision. But they will fight like cats and dogs over who gets the credit for it. The centrists and the reformists — i.e., Rafsanjani and Mousavi — do not want Ahmadinejad to gain international legitimacy by striking a breakthrough deal with the West.

Hillary Clinton, speaking to CNN from Pakistan, sensibly sounded less than alarmist about Iran’s back-pedaling, even as various hawks condemned Iran’s maneuvering. Said Clinton:

“We are working with the IAEA (the U.N. International Atomic Energy Agency), with France, Russia … who are all united and showing resolve in responding to the Iranian response and seeking clarification. So I’m going to let this process play out.”

Still, the question must be asked, What exactly does she mean by “let this process play out.” Clinton, among the more hawkish players in the administration on Iran, may well have concluded that as soon as the talks run into a roadblock, it will be time to seek tougher new sanctions on Iran — including a gasoline and refined petroleum products embargo. Other harsh sanctions are being prepared, and knee-jerk hawks in Congress are reading legislation.