As the Islamic State (IS) has been in steady retreat, Iran and Russia are facing real difficulties sustaining their partnership. Each took advantage of the fight against IS to further its military campaign in Syria.
Both sides avoid discussing their differences, keeping their critics from making the most of the situation, but both fail to completely conceal the friction. In 2016, Moscow and Tehran jointly shielded Syrian President Bashar al-Assad's regime from the opposition and sought to preserve the remaining state institutions. In an attempt to freeze the six-year-long civil war, Russia is currently opting for agreements beyond the peace talks in Astana, Kazakhstan — that is, behind Iran’s back. Examples include the de-escalation zone in southwest Syria that Russia negotiated with the United States in Amman, Jordan, as well as de-escalation zones in eastern Ghouta and northern Homs, both of which were negotiated in Cairo.