Now that the tide in the Syrian civil war appears to have definitely turned in favor of President Bashar al-Assad’s regime, one of the key factors that will shape Syria’s future is the precise nature and durability of the relationship between the two countries that saved Assad from collapse: Iran and Russia.

Tehran and Moscow worked together to bolster Assad, but the character of their ad hoc alliance has always remained a bit of a mystery. They each, for their own purposes, wanted the regime in Damascus to survive. Beyond that, it has never been clear just how committed Russian President Vladimir Putin has been to his links with the Islamic Republic. ...