After the death of senior Daesh operative Abdurakhmon Uzbeki as a result of a U.S. Special Forces raid in Mayadin, an eastern Syrian city around Deir ez-Zor last week, the complexity of the Daesh threat to Turkey was again proven. A U.S. military statement acknowledged that Uzbeki was the "facilitator" of the Reina nightclub attack on New Year's Eve. Furthermore, he was a "close associate" of Abu Bakr al-Baghdadi, the self-proclaimed "caliph" of the terror group, and he had a "key role" in coordinating external terror plots, the movements of foreign fighters and organizational funding activities. Involvement of such a high-profile operative in an attack in Turkey implies that Daesh attacks in Turkey have a firm chain of command directed from headquarters in Syria or Iraq. Generally, leadership decapitation greatly contributes to the dissolution of terrorist organizations, however, Daesh can survive this type of damage due to its strategic flexibility. Rejuvenation of the leadership cadre could ensure that Daesh can sustain external military operations; thus, leadership-coordinated and sleeper-cell-supported Daesh attacks may still be a great danger for Turkey's national security, stability and social harmony as was the case at Reina. Thus, sleeper cell threat containment is the most pressing national security issue to resolve before it becomes too late.

THE THREAT AFTER LOSING TERRITORIALITYSleeper cells committed to Daesh are the most significant threat in the aftermath of a Daesh defeat in Iraq and Syria. They have already proved how real that danger is by carrying out shocking surprise attacks in eastern parts of Mosul where Iraqi forces thought that Daesh elements had been cleared. A similar incident occurred in Kirkuk in October 2016 when hidden Daesh militants equipped with sniper rifles, machine guns and suicide vests launched a surprise attack in the city. Operation Euphrates Shield has ensured that no Daesh militant will be able to slip across the border into Turkey. The extraordinarily long period of time without a Daesh attack in Turkey from Aug. 20 to Jan. 1 has demonstrated that the former's ability to launch attacks was interrupted by the latter thanks to much stronger security along the Turkish-Syrian border, preventing militants and weapons from slipping into Turkey. However, neutralization of Daesh activities along the border inextricably increased the significance of sleeper cells for the terrorist group.

Sleeper cells are different from hit squads. The latter infiltrate a target country shortly before launching an attack. However, a sleeper cell is well placed and immersed in society. A sleeper cell consists of a small group of militants who maintain their lives in ordinary ways and appear legitimate to avoid detection, waiting for appropriate circumstances to take action in order to gain the best outcome from the attack. For instance, Turkish police operations after the Reina attack revealed that members of uncovered cells were introducing themselves as doctors, dentists, businessmen or artisans. A sleeper cell may be an autonomous structure, however, it usually takes action due to incoming orders. Generally, members of sleeper cells have no ties to each other or knowledge of other cells in the country to ensure that an arrested militant cannot be transformed into an informant.

The Reina nightclub attack was carried out by a sleeper cell-supported, professionally-trained Daesh foreign fighter living in Turkey for about a year, rather than a highly mobilized hit squad that entered Turkey from Syria shortly before the attack, as was the case for most previous Daesh attacks in Turkey. It is remarkable the extent to which Abdulgadir Masharipov had relied on support from sleeper cells in Konya, İzmir and Istanbul when planning and conducting the attack. Therefore, the nightclub attack was a certain Daesh operational shift with strategic national security implications, and more importantly, it represented the specific pattern of future attacks in the country.

TURKEY'S COUNTERTERRORISM EFFORTSDaesh sleeper cell members in Turkey have varying backgrounds in terms of nationality and organizational status. The geographical proximity of Turkey to the inner circle of Daesh, the region encompassing both Syria and Iraq, caused this diversification, exacerbating the threat by mixing all types of elements of Daesh, including group leaders, veteran fighters and Turkish recruits. Group leaders are generally responsible for sleeper cell coordination according to directives from headquarters, and veteran fighters are battle-hardened militants who are the potential perpetrators of future attacks, while Turkish recruits provide background info due to their local knowledge to create appropriate conditions for an attack. Although it is not possible to identify a certain type of sleeper cell profile in Turkey because of the lack of concrete evidence, it is safe to claim that most consist of Syrians and Iraqis. However, noticeably, groups from the Caucasus and Central Asia have increasingly been targeted by police operations in the country.

Security operations against Daesh in the homeland have been one of the major components of the former's fight with the latter. Especially after the Reina attack, the intensity and scale of operations have skyrocketed. Many leaders were captured and imprisoned while many terrorist cells were uncovered. However, undoubtedly, the terrorist group still has a significant capacity to strike Turkey, and sleeper cells are possibly the most vital instruments to achieve that.

For Turkey to meet this volatile threat, some crucial efforts may be implemented or intensified. Closely tracking movements of militants and weapons, tracing communications between group members, cutting off cash flows and obtaining intelligence from arrested militants are measures that have been implemented by national intelligence agencies and police forces. These measures must be boosted and widened. In the past, the rapid collection of intelligence, increasing readiness among police forces and joint special operations ensured effective results against terrorist cells. Furthermore, raising awareness in society would contribute greatly to counter-terrorism efforts by building societal resilience, especially in the long-term. Already, several police raids have been conducted due to incoming information. Thus, maintaining and broadening current policies and developing awareness in society will significantly help contain possible Daesh sleeper cells.

* Research assistant, SETA Foundation