Key Takeaway: ISIS has established a stable territorial base in the mountainous regions of the Central Syrian Desert and has begun to overtake pro-Assad regime forces in the area. ISIS is waging a coordinated campaign to draw pro-regime forces into an untenable security posture in defense of energy and oil assets threatened by ISIS. Assad’s Russian and Iranian backers have attempted to contain ISIS’s insurgency but are unwilling to commit force at the scale necessary to succeed. ISIS is already using its territorial base to destabilize other parts of Syria. ISIS could attempt to seize new territory or financial assets in central Syria during its Ramadan campaign beginning in April 2021.

ISIS has begun to overtake pro-regime forces in the Central Syrian Desert. ISIS controls several small swaths of territory from which it is conducting a coordinated campaign across multiple zones of the Central Syrian Desert (CSD). The Central Syrian Desert encompasses rough terrain studded with oil and gas assets and crisscrossed by ground lines of communication (GLOCs) that connect regime-held population centers. ISIS’s strongholds are located in mountainous terrain overlooking those GLOCs and the desert’s few population centers, indicated in figure 1. ISIS has successfully defended these strongholds when pressured, demonstrating sustainable control of rural terrain. In one instance, Russian-backed Syrian Arab Army 5th Corps units, likely with elite Tiger Forces support, attempted to clear an ISIS control zone northeast of Rahjan, Hama Province, on December 13, 2020. ISIS ambushed the clearing unit and forced it to retreat, preventing the unit from recovering its wounded until the arrival of air support hours later.

Figure 1

From its strongholds, ISIS has applied consistent military pressure against pro-regime forces’ internal supply lines within the Central Syrian Desert, jeopardizing their operations across most of Syria. ISIS regularly conducts complex ambushes on regime convoys at five key chokepoints along GLOCs that connect pro-regime bases and oil/gas infrastructure in Deir ez-Zour, Raqqa, Hama, and Homs provinces. These attacks cause tens to low-hundreds of regime casualties monthly according to available reporting and analysis from open-source researchers. In order to supply bases around the desert and in Palmyra, pro-regime forces will have to continue to suffer these manpower losses or dedicate scarce air units to transport and supply their forces, as Russian units are already doing for themselves. ISIS likely also extorts and disrupts commercial traffic along these routes, depriving the regime of revenue. The US-led coalition conducted at least one airstrike against an ISIS training camp in the CSD in October 2020, demonstrating growing coalition recognition that pro-regime forces are failing to contain ISIS’s resurgence.

ISIS’s campaign threatens key Syrian oil and natural gas infrastructure and is forcing the pro-regime coalition to overextend its manpower to secure these facilities. ISIS has repeatedly attempted to take key oil and gas infrastructure in the CSD. ISIS successfully seized the Doubayat gas field three times in September and October 2020. The field is 12 miles south of al Sukhnah, one of the two major population centers in the eastern Homs Desert. The regime recaptured the field each time and now holds it. However, two of those recapture operations required Russian air support, indicating that Syrian units may not be able to retake the field independently in the future. ISIS has also laid improvised explosive devices (IEDs) around energy infrastructure, including the al Taym and al Tayba oil fields, to limit the mobility of pro-regime forces securing the area. Al Taym oil field is 10 miles south of Deir ez-Zour City and hosts a base for Russian-backed forces; Tayba oil field is 15 miles north of Sukhna. ISIS’s pressure is forcing pro-regime forces to regularly redeploy high-end assets to recapture seized fields.

Pro-regime counter-ISIS operations are plagued by the same constraints that limit other pro-regime campaigns across Syria:

  • Limited operational capacity. Pro-regime forces can only mass capable forces in one area of responsibility at a time, leaving security gaps for ISIS to exploit. ISW has reported on the consistent inability of pro-regime forces to operate simultaneously across multiple fronts.
  • Manpower deficits and incompetent conscripts. The Assad regime does not have the manpower to perform capable area security. Neither Russia nor Iran is likely to invest the manpower necessary to secure the CSD. Russian units, including Wagner Private Military Forces deputized by the Russian government, are formally responsible for securing multiple oil fields in the area but do not perform wider area security. The Syrian regime often tries to fill this gap by sending ill-trained hired or conscripted troops to hold untenable positions deep in the desert, further weakening the regime’s footing and making the Central Syrian Desert deployment infamously undesirable.
  • Russo-Iranian friction. ISIS has exploited and fueled tensions between Russian and Iranian-backed units. ISIS assassinations of members of rival factions have led those factions to accuse one another of providing information to ISIS. These assassinations exacerbate preexisting squabbles over control of the CSD’s valuable resources. Russian forces agreed to transfer security positions near valuable phosphate fields and along high-volume GLOCs between Sukhna and Palmyra to Iranian proxies to appease Iranian demands on January 26. Poorly equipped Iranian-backed proxies replaced Russian-backed units around Palmyra after the agreement, creating vulnerabilities that ISIS has exploited.

    ISIS’s pressure is preventing elite and mobile pro-regime units from taking the initiative in the counter-ISIS fight. ISIS is exploiting the regime’s vulnerabilities to attack key Russian and Iranian bases across multiple zones to force the limited capable and rapidly deployable pro-regime units, including the Tiger Forces, to respond defensively across multiple zones in succession, as seen in figure 2. For example, ISIS carried out a large explosive attack–possibly using a vehicle-borne improvised explosive device (VBIED)–on al Taym oil field, 10 miles south of Deir ez-Zour City, on February 3 to compel Russian-backed forces to abandon an operation against the ISIS stronghold in Jabal Bishri and redeploy to secure the field. Then, as those units became fixed at al Taym oil field, ISIS attacked oil facilities in Fasida, 20 miles southeast of Ithriya, on the same day. ISIS’s successive, geographically disparate attacks deny the regime opportunity to counter ISIS pro-actively.
Figure 2

New Russian-led efforts to contain ISIS have not meaningfully restricted the militants’ territorial grasp in Central Syria. Russia began a new effort to contain ISIS in the CSD in August 2020. Russian-led operations with elite Syrian proxies have focused on securing a few key oil assets including al Doubayat, al Shoula, and al Taym Oil Fields. Attempts by Russian-backed units to re-establish secure GLOCs to those fields have been unsuccessful. For example, ISIS resumed ambushes along the “secured” Khanasir-Ithriya highway just weeks after Russian-sponsored clearing operations ended in September 2020. Similarly, ISIS attacked a Russian-backed unit along the Deir ez-Zour-Palmyra highway near Kabbajab on February 18, 2021, three weeks after Deir ez-Zour National Defense Forces leader Nizar al Khidr declared the highway “secure.” Russia’s Ministry of Defense has asserted that it is achieving success against ISIS, claiming to have killed 327 ISIS militants in a several-day air campaign in August 2020. ISIS deaths in Russian air campaigns cannot be substantiated and, given the minimal impact of those campaigns on the security situation, are almost certainly exaggerated.

ISIS’s pressure in the CSD has begun to disrupt pro-regime operations in vital population centers outside the desert. The reallocation of pro-regime military resources to central Syria is already thinning the regime’s front lines in Idlib and the Hama-Homs corridor as pro-regime forces redeploy from these areas to the CSD. Russia also redeployed the Russian-backed 5th Corps 8th Brigade from Dera’a to the CSD on February 26, weakening the Russian effort to stabilize southwestern Syria. ISIS is also threatening pro-regime forces’ ability to reinforce front lines with Turkey north of Raqqa City.

ISIS pressure has forced the regime to turn to Russia and Iran for increasing economic and military support. ISIS attacks on energy infrastructure have driven up oil prices and limited oil access, worsening the economic collapse in regime-held Syria and fueling growing instability in loyalist areas. Russia and Iran have seized this opportunity to expand their military presence along the Euphrates River Valley, provoking more resource competition within the pro-regime coalition but also increased Russian and Iranian recruitment from the Arab tribes in SDF-held Syria, potentially threatening the SDF’s control.

ISIS is exploiting the regime’s newly thinned defenses and attacking key villages in Hama. ISIS temporarily seized populated terrain near the town of Rahjan three times between October 2020 and January 2021, forcing civilians to flee the area and setting up multiple layers of defense to block the regime’s counter-attack. Rahjan is key terrain that hosts a regime base. If ISIS seized the town itself, the group would be able to threaten regime GLOCs through Ithriya, the key node of regime transit between Idlib and Raqqa provinces. The regime has recaptured the terrain each time, but in two cases was only able to do so by redeploying additional units to the area and calling in artillery support and Russian airstrikes. In a sign of the regime’s failing defenses, the regime was incapable of sending elite Tiger forces to secure Rahjan and instead attempted to organize local tribes into an anti-ISIS militia after the October 2020 seizure. The militia likely lacks the skills and equipment to prevent ISIS from retaking this terrain, thus reinforcing its dependence on Russian air support, which is in short supply. Future ISIS attacks in this area are likely. ISIS’s central media has thus far refrained from claiming land seizures in Rahjan, possibly indicating that ISIS is wary to do so until it can hold the terrain.

ISIS may scale up efforts to seize populated terrain and oil infrastructure in the coming months, including during Ramadan from April 12 to May 12, 2021. ISIS typically launches a surge in operations during Ramadan that includes major attacks that surpass the prior baseline of activity. This year, ISIS is well-positioned to scale up its attacks on oil infrastructure, potentially seizing multiple facilities–including the T2 oil pump station 40 miles west of Albu Kamal along the Iraq-Syria pipeline or the al Hayl or Tuweinan gas refineries. In a most dangerous scenario, ISIS and pro-regime forces could reach some accommodation in central Syria that allows ISIS to retain control of oil or gas facilities if it decreases pressure on regime GLOCS and pivots to surge in other areas the regime wants destabilized. ISIS could alternately launch a new attempt to seize rural towns or to attack into urban centers thus far secured by pro-regime forces, including Sukhna or Palmyra.

ISIS is positioned to expand its campaign outward from the CSD. ISIS could move north from the CSD to further undermine Turkish-backed governance and strengthen smuggling routes across the Turkish-Syrian border. ISIS already escalated attacks in Turkish-controlled portions of Aleppo Province in June 2020 after two years of relative inactivity in that zone. As ISIS continues to expand westward into Hama, ISIS cells could also begin to threaten pro-regime transit along the M5 highway, which would cause a major economic disruption that the regime cannot afford. ISIS has similarly begun to expand out of the CSD to the southwest: ISIS cells in the CSD attacked energy infrastructure between al Dumayr and Adra, 20 miles northeast of Damascus, in August of 2020, causing blackouts along the entire Syrian coast. ISIS conducts regular assassinations and possibly explosive attacks in loosely regime-held Dera’a and is likely overlapping campaigns with anti-regime forces and intra-regime feuds from its base in the CSD. ISIS could use its nascent base southwest of Palmyra, near Quryatayn, to escalate attacks on regime positions outside Damascus or through Suwayda to Dera’a. Finally, ISIS can also pivot east. ISIS is already using its positions in regime-held Deir ez-Zour to infiltrate and destabilize SDF-held areas. ISIS could expand its control from Faydat in the northeastern CSD, along the road to Mayadin, from which it could launch attacks to attempt to seize SDF-held villages across the Euphrates from Mayadin.

By: Eva Kahan