This post is an extract taken from Prime Source's latest weekly regional assessment
Recent Development: Pro-regime forces have made significant advances in central and eastern Syria, in their overall efforts to capture most of Eastern Syria. After isolating several ISIS held pockets in central Syria, and with the help of Russian ground and air force, pro-regime units entered the city of Uqayribat, ISIS’s main stronghold in central Homs. In Eastern Syria, pro-regime forces have also launched an offensive west of Deir ez-Zor, capturing several locations placing them 30 km away from Deir ez-Zor on September 2-3. On September 3-5, in a final push, pro-regime forces reached Deir ez-Zor, which had been under ISIS siege since 2014.
This comes as a US military officer reportedly stated in a briefing that the final battle against ISIS would take place in the Middle Euphrates River Valley (the region between Deir ez-Zor and Albu Kamal), adding that the US saw the Kurdish-led Syrian Democratic Forces (SDF) as the more suitable force for this battle and indicating that several rival forces were also rushing to capture the area.
Finally, during the past week, the SDF made significant progress in Raqqah by launching a two-pronged offensive in the southwestern part of the city, which created an ISIS pocket the US-backed group is currently clearing (see Raqqah map below).
Analysis: With pro-regime forces now poised to take on ISIS in the city of Deir ez-Zor, the window of opportunity for a US-backed offensive to capture the northeastern bank of the Euphrates River is closing quickly. The breaking of the siege represents an important step in pro-regime efforts to secure Eastern Syria and possibly reach the Iraqi border before any other rival forces. The fact that the regime was able to do so even before the US-backed SDF could start its own offensive provides Assad, and his Iranian allies, with a significant advantage and highlights the importance of the area for both Iran and Assad. With the offensive against ISIS in Uqayribat reaching its conclusion and Hezbollah’s own border operation now over, pro-regime forces will likely focus all their attention in Deir ez-Zor – provided they are not distracted by an opposition attack in Western Syria. With enough momentum, the regime can decide to cross the Euphrates River as soon as possible, in a bid to pre-emptively thwart any US attempt to capture the northeastern bank of the Euphrates.
Indeed, despite the implementation of a de-confliction line along the Euphrates between the US and Russia, Damascus and Tehran may be tempted to test Washington’s resolve in enforcing it. Pro-regime forces likely aim to capture several critical oil fields situated northeast of Deir ez-Zor and then push toward the Iraqi border – if they are allowed to. They are all the more likely to do so as Washington has sent mixed messages regarding its willingness to counter Iran influence in this area and prevent it from securing the Iraq-Syria border. There has been no clear decision from Washington to actively counter such a project, while several officials belonging to the US-led anti-ISIS coalition have stated that their focus was to fight ISIS - one even stating that the coalition would be happy if the regime captures this key area of Eastern Syria as long as ISIS is defeated.
This means that despite a series of incidents, including the shooting down of several Iranian-made drones in southern and northern Syria, Washington has yet to clearly signal its resolve to act more forcefully and prevent Iranian-led forces from reaching the Iraqi border. Whether the US statements regarding an upcoming SDF offensive in Eastern Syria stems from the fact that a decision has been made or not, the fact that Washington has thus far shown little resolve to tackle the Iranian threat there will likely embolden Iranian-led forces and heightens the chance for confrontations similar to the ones involving Iranian-made drones - should Washington finally give the green light to an SDF operation in Deir ez-Zor.