The striking thing about Hassan Rohani’s election as Iranian president was that Ayatollah Ali Khamenei felt obliged to allow his first round victory to stand. It would have been easy to “lose” enough of Mr Rohani’s vote to push it below 50 per cent. If nothing else, forcing a second round would have given the hardliners a chance to regroup.

Presumably, the supreme leader feared a reprise of the green movement protests that followed blatant vote rigging in favour of a second term for Mahmoud Ahmadi-Nejad in 2009. Perhaps Mr Khamenei had been casting a glance over his shoulder at Istanbul’s Taksim Square. The unrest in neighbouring (and democratic) Turkey was a timely reminder of the combustible combination of disenchanted youth and digital technology.

Whatever the calculation, this tilt in the political balance in Tehran matters. The brutality in Syria has commanded the world’s attention. The challenge posed by Iran is of a different order. Grave as it is, the impact of the Syrian fighting on wider international security is slight when set against the implications of Iran’s nuclear programme.