Supreme Leader Ali Khamenei's control of Iran is hardly as supreme as his title might suggest. The Islamic Republic's internal decision-making process is often hidden from view, but stern words from Ayatollah Khamenei this week were a graphic reminder that domestic politics as much as foreign-policy intransigence has led Tehran to it present impasse.
Provoked by an escalating war of words among leaders of the judicial, legislative and executive branches, Ayatollah Khamenei did not mince words. "I warn the heads of the three branches to mind their own business," he said on Wednesday. Until next June's presidential election is over, he warned, anyone "exploiting emotions of the people" by divisive statements would be "committing treason".
The immediate cause of these hard words was a complaint by President Mahmoud Ahmadinejad, whose power is waning as his second four-year term draws to a close, against Chief Justice Sadegh Larijani, who has refused the president permission to visit an aide who is languishing in Tehran's Evin prison. The top judge has a strong ally in his sibling Ali Larijani, the speaker of Parliament. The Larijani brothers are often considered to form their own centre of gravity (one of many) in Iranian politics.
In democracies, partisan wrangling is commonplace. But Iran's governance is unusual, to say the least, with a religious leader deemed supreme and a powerful clergy in Tehran and Qoms, alongside a president and the normal array of ambitious party figures. The questionable veracity of the state media makes an already complicated milieu of governance often impenetrable to the outside observer.
Add in the Revolutionary Guard, which protects its own vast business empire, and the result is a murky, ponderous political system.
Few were surprised, then, by reports of widespread fraud in the 2009 presidential election, or at the violent repression of "Green" protests against vote-rigging by students and the urban middle class.
Negotiations with Iran over its ambiguous nuclear programme have often seemed maddeningly contradictory, with a seeming breakthrough always followed by an about-face. It's worth remembering that exhaustive international talks must be followed by equally fractious give-and-take among Tehran's factions. That second round of negotiations may often trump the first.
At a time when diplomacy is needed, quite possibly to avert a war, Iran's dysfunctional decision-making is everybody's problem. The unenviable task of its negotiating partners is to help the country avoid becoming its own worst enemy.