The story so far, in case you missed it, is that US authorities have announced that an Iranian-American car salesman, Manssor Arbabsiar, tried to enlist a DEA informant to commit mass murder in the mistaken belief that he was a hitman working for a Mexican drug cartel. One of the crimes Arbabsiar is alleged to have had in mind was the murder of the Saudi envoy in Washington, Adel al-Jubeir.

‘What we know is that an individual of Iranian-American descent was involved in a plot to assassinate the ambassador to the United States from Saudi Arabia,’ President Obama said at a press conference on 13 October. ‘And we also know that he had direct links, was paid by and directed by individuals in the Iranian government.’ Peter King, a right-wing Republican congressman, called the plot an ‘act of war’. Vice-President Joe Biden said that ‘all options are on the table’.

In an interview with al-Jazeera this week, President Ahmadinejad denied the allegations and said the evidence was ‘probably fabricated’. Well he would, wouldn’t he. But plenty of observers agree that the alleged plot doesn’t fit with the Quds Force’s usual way of doing things.

Everyone has bad days, but why would any bona fide secret agent, even some kind of rogue operative, who went to Mexico apparently for deniability, volunteer so much information about his background, mission and accomplices to the hitman he was hiring? If Arbabsiar were a trained agent working for the Quds Force, would he be dimwitted enough to think that money wired from Iran to a Mexican drug cartel wouldn’t attract the attention of the US authorities? When Arbabsiar discusses buying a car with his alleged handler in Iran, investigators claim that he is confirming the plan to kill al-Jubeir. But is it really plausible that a senior Quds Force leader would give orders to kill the Saudi ambassador, even in code, on an open phone line to the United States?

One analyst, reading between the lines of the amended criminal complaint, has argued that the DEA informant may have suggested killing al-Jubeir to Arbabsiar, rather than the other way round. Whoever’s idea it was, the murder would make little strategic sense for Iran. Attempting to assassinate the ambassador, in Washington of all places, would be taking a huge risk for a relatively minor target, who isn’t even a member of the royal family. Whatever the truth behind the ‘plot’, the only certainty is that the fallout from it has further damaged relations between Iran and the United States, to the satisfaction of hardliners on both sides.