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.

In July, US President Donald Trump and Russian President Vladimir Putin agreed on the sidelines of the G-20 summit in Hamburg to establish a cease-fire in southwestern Syria, in the Daraa, Quneitra and Suwayda provinces, which virtually annulled the terms established at Astana of creating a southern de-escalation zone. The latter included Suwayda rather than Daraa and Quneitra. According to some sources, the US-Russia deal demands that pro-Iranian forces pull back at least 40 kilometers (25 miles) from the Israeli-Jordanian border, with Russia’s military police deployed on the ground. In the region, Moscow seeks to garner the support of the local population, even seeking to form loyal militias.

The separate agreement signed in Cairo between Russia and Islamist opposition faction Jaish al-Islam made it possible for Russian troops to run checkpoints in eastern Ghouta — an interesting development given that Turkey had officially stated in June that Russia and Iran would deploy forces to the Damascus area to monitor the cease-fire. It is hard to discern whether Russia has unilaterally revised the scenario developed by the Moscow, Tehran and Ankara working groups. However, a revision is definitely implied by Russia’s efforts to gain control of the situation in the Damascus region, where Assad’s forces and Iran-backed militias have tried different strategies to recapture opposition-held territories.