The conclusion of an agreement between Turkey and the U.S.-led anti-ISIS coalition to open Turkish airbases for coalition aircraft conducting sorties against the Islamic State of Iraq and al-Sham (ISIS) marks a major shift in Turkish policy which will provide immediate boost to U.S. efforts to degrade and ultimately defeat ISIS. At the same time, Turkey began launching airstrikes and internal crackdowns targeting members of both ISIS and the outlawed Kurdistan Workers’ Party (PKK) in the wake of several days of violence which included an ISIS-linked SVEST attack inside Turkey and several PKK-linked assassinations of Turkish police officers. Turkey’s decision to escalate against both militant groups suggests that Turkey intends to leverage the coalition’s calls for further action against ISIS in order to assert its own strategic interest in limiting the expansion of armed Kurdish groups along the Turkish border. The government of Turkish President Recep Erdogan may also seek to utilize these security threats to increase its own political standing amidst ongoing negotiations to form a coalition government and a potential call for early elections. Over the near-term Turkey will face an expanded domestic threat from both ISIS and PKK militancy in the form of persistent violence against the Turkish state. Nonetheless, a sustained Turkish effort against ISIS’s networks in Turkey and northern Syria combined with the efforts of local anti-ISIS Syrian opposition forces has the potential to significantly disrupt the foreign fighter flows which provide ISIS with a key source of reinforcements, suicide bombers, and legitimacy as a global caliphate.

The Deal

Turkey significantly increased its participation in the U.S.-led anti-ISIS coalition in a marked shift from its previous hesitancy to directly engage the Islamic State of Iraq and al-Sham (ISIS). The Turkish Ministry of Foreign Affairs released a statement on July 24 confirming that Turkey and the U.S. had agreed to “further deepen their ongoing cooperation in the fight against ISIS” following a telephone conversation between U.S. President Barack Obama and Turkish President Recep Erdogan on July 22. Although the exact details of the deal remain unknown, President Erdogan confirmed that the Turkish government granted the U.S.-led anti-ISIS coalition access to the strategic Incirlik and Diyarbakir Airbases in southern Turkey “within a certain framework” in a move long sought by the U.S. to stage operations near Syria. The opening of these bases would sharply reduce the distance that coalition aircraft must transit to strike ISIS targets in Syria, allowing for an increased rate of daily combat sorties. The Turkish government also reportedly authorized the U.S.-led coalition to utilize airbases in the southern cities of Batman and Malatya for emergency situations.

Unverified Turkish sources indicated that the deal also included provisions for an “ISIS-free” zone extending forty to fifty kilometers into ISIS-held regions of Aleppo Province in northern Syria in order to attack ISIS in greater depth within Syrian territory. Turkish and U.S.-led coalition aircraft would perform “attacking or exploration” missions over the zone “as needed” in order to prevent advances by ISIS or Syrian al-Qaeda affiliate Jabhat al-Nusra (JN). The exact parameters of this claimed zone have not yet been clearly defined in the public record. Although some Turkish sources referred to the region as a no-fly zone and claimed that Syrian regime aircraft entering the zone would also be targeted, U.S. officials including U.S. Special Envoy to the Anti-ISIS Coalition Gen. John Allen (ret.) denied that the implementation of a no-fly zone had been “part of the discussion.”

The Turkish Ministry of Foreign Affairs also announced that Turkish warplanes will directly participate in the international anti-ISIS coalition air campaign for the first time. Turkey launched the opening salvo of this expanded role in the morning of July 24 as three Turkish F-16 fighter jets departed from Diyarbakir Airbase in south-central Turkey and conducted three airstrikes against ISIS targets in the Syrian border town of Hawar Kilis north of Aleppo City. Turkish media sources reported that the strikes comprised part of a newly-declared Turkish military operation named “Martyr Yalcin” after a Turkish non-commissioned officer killed during a gunfight with ISIS militants along the Syrian border on July 23. A second round of Turkish airstrikes on the night of July 24-25 also targeted positions of the outlawed Kurdistan Workers’ Party (PKK) militant group in northern Iraq for the first time since 2011, effectively ending a two-year ceasefire agreement between the PKK and the Turkish government. Turkish Prime Minister Ahmet Davutoglu stated that the airstrikes were not an isolated incident but rather part of an ongoing “process” to address threats along the Turkish border. Nonetheless, one Turkish government official speaking to Reuters later noted that “we can't say this is the beginning of a military campaign, but certainly the policy will be more involved, active and more engaged.” These statements imply that Turkey intends to sustain its activities against ISIS and the PKK over a long-term campaign.

Why Now?

The outlines of this agreement between the U.S. and Turkey appear to have been laid during a visit to Turkey by Gen. John Allen (ret.) and U.S. Undersecretary of Defense Christine Wormuth on July 7-8. Unconfirmed reports at the time suggested that the talks had resulted in preliminary approval for the coalition’s use of Incirlik Airbase after Turkey received assurances that the U.S. would consider Turkish proposals for a buffer zone in northern Syria and block any attempt by Syrian Kurdish forces to move into areas along the Turkish border west of the Euphrates River. These accounts suggested that Turkey had offered a major concession by dropping its long-standing insistence that the international coalition expand its air campaign against ISIS to include airstrikes against the regime of Syrian President Bashar al-Assad. This rebalancing suggests that recent developments may have led the Turkish government to prioritize the internal security threats posed by ISIS and the PKK over Turkey’s regional concerns regarding Iranian expansionism and the enduring presence of the Syrian regime.

The successful conclusion of these negotiations following months of talks likely came as a product of the intensifying security concerns facing the Turkish government. Turkey had previously avoided overt confrontation with ISIS and other militant groups transiting through its territory in order to apply indirect pressure to both the Syrian regime and the Syrian Kurdish YPG, which the Turkish government views as an offshoot of the PKK. This stance also enabled Turkey to limit the potential for violent terrorist attacks within its borders by providing an incentive for ISIS and other extremist groups to avoid jeopardizing their supply routes through Turkey by disrupting the status quo. Although the existence of these transit pathways represented an implicit threat to Turkey, the seizure of the border town of Tel Abyad in northern Syria from ISIS on June 15 by Kurdish YPG forces appears to have been the primary trigger which forced Turkey to reevaluate its security policies. The prospect of further gains along the Syrian-Turkish border by PKK-linked Kurdish forces directly supported by the U.S.-led coalition likely generated the impetus for Turkey to further engage with the anti-ISIS coalition in order to ensure that the coalition campaign would evolve in line with Turkey’s own strategic interests.

The Turkish government soon moved to link its concerns regarding the Kurds to the security threat posed by ISIS in a likely attempt to attract buy-in from the U.S.-led anti-ISIS coalition for the imposition of limits on further Kurdish expansion. President Erdogan called security meetings with senior Turkish government and military officials on June 17-18 which established “red lines” for further Kurdish expansion in Syria. The Turkish National Security Council held additional meetings to address the threat posed by ISIS, and on June 29 an advisor to Prime Minister Davutoglu stated that the meetings would likely result in a change to the Turkish military’s rules of engagement that would authorize attacks against ISIS fighters inside Syria near the Turkish border. Over subsequent weeks Turkey reinforced its border with largenumbers of soldiers, armored vehicles, and artillery units, placing a particular concentration in Kilis and Gaziantep Provinces opposite ISIS-held areas of Aleppo Province in Syria. By July 22, Turkish media reported that half of Turkey’s border security personnel and armored cars as well as 90% of Turkey’s drones had been deployed to the Syrian border. Meanwhile, Turkey also began a crackdown against suspected ISIS members or sympathizers inside Turkey. President Erdogan noted on July 10 that nearly 1,300 foreigners had been arrested and deported on suspicion of involvement with ISIS.

These security concerns dramatically escalated on July 20 after a suspected ISIS member conducted a spectacular SVEST attack against a group of pro-Kurdish student activists in the southern Turkish town of Suruc on July 20, killing at least thirty-one individuals and wounding over one hundred others. Kurdish activists linked the bombing to a similar double IED attack against a Kurdish political rally in Diyarbakir on June 6 which killed four individuals and wounded at least 400 others, raising the prospect of an incipient ISIS campaign to target Kurds inside of Turkey. This message was reinforced with the release of the second issue of ISIS’s Turkish-language Constantinople magazine on July 21 which contained a warning that Kurds fighting ISIS in Iraq and Syria “may fight in Turkey in a similar way in the not too distant future.” In response, Kurdish militants engaged in their own campaign of targeted violence against alleged ISIS “collaborators”, triggering a major amplification of violence within Turkey. The PKK claimed responsibility for the execution of two Turkish police officers with a claimed association to ISIS in the border town of Ceylanpinar on July 22. Suspected PKK members also killed another Turkish police officer in an ambush in Diyarbakir, while members of the PKK youth wing executed an alleged ISIS member in Istanbul. Turkish security forces also discovered IEDs in front of two offices of the ruling Justice and Development Party (AKP) of President Erdogan in the Turkish capital of Ankara and the southwestern Turkish province of Hatay. Kurds and Turkish opposition parties held large streetprotests in Istanbul, Ankara, and several other Turkish cities which in some cases devolved into violence.

The threat posed by this spiral of violence likely played a role in expediting the final agreement between the U.S. and Turkey. On June 24, simultaneous with the implementation of the agreement, Turkish security forces launched a wave of arrests targeting suspected ISIS, Kurdistan Workers’ Party (PKK), and leftist Revolutionary People’s Liberation Party-Front (DHKP-C) members throughout thirteen Turkish provinces which detained at least 297 individuals. Local media reported that the raids involved thousands of police officers and Special Forces soldiers supported by helicopters. CNN Turk reported that anti-terror police raided over 140 locations in the major city of Istanbul alone, detaining ninety individuals including thirty foreigners. The office of Prime Minister Davutoglu later released a statement pledging to fight all transnational “terrorist” groups “without distinction.” A senior Turkish official characterized the airstrikes in Syria and the domestic raids as dual “preventative measures” conducted in line with a policy decision to “move to active defense from passive defense” that had been formalized during an emergency “Special Security Meeting” on July 23. This confluence of events may have provided the final stimulus for Turkey to adopt a more aggressive stance against ISIS in exchange for the acquiescence of the U.S.-led coalition towards Turkish military action against the PKK.

The timing of the start of combat operations against both ISIS and the PKK may also have been driven by domestic Turkish political concerns. President Erdogan and his ruling AKP Party have come under heavy criticism from domestic opponents for their foreign policy towards Syria, which included a permissive attitude towards ISIS, JN, and other extremist groups fighting the Assad regime in Syria. These mounting criticisms came to a head during the Turkish general elections on June 7 in which the AKP lost their overall majority in the Turkish Parliament amidst historic gains for the pro-Kurdish People’s Democratic Party (HDP). This development raised the potential for a shift in Turkish policy towards the Syrian Civil War as Turkish opposition parties pressed the AKP to reduce its hostility towards Syrian President Bashar al-Assad, limit its support to Syrian opposition factions, and establish positive relations with Syrian Kurds. Nonetheless, ongoing negotiations between the AKP and rival Turkish political parties to form a coalition government do not appear to be gaining traction and a call for early elections in Turkey appears likely. Expanded Turkish participation in the anti-ISIS coalition may thus serve a political goal for President Erdogan and the AKP by undercutting criticism of government policy towards ISIS and rallying the Turkish populace in the face of domestic security threats. The increase in violence attributed to the PKK and other Kurdish militant groups will also likely erode the position of the HDP to the benefit of the AKP. If early elections are called, these effects could improve the AKP’s vote share sufficiently to allow the AKP to regain its outright parliamentary majority and advance its Syria policy unhindered.

Implications

The expansion of Turkey’s role in the U.S.-led anti-ISIS coalition will almost certainly generate an immediate reaction in the form of retaliatory attacks from ISIS or ISIS sympathizers operating inside of Turkey. Thousands of foreign fighters have utilized Turkey and its porous border with Syria as a pathway to join with ISIS forces in Syria and Iraq, including an estimated 1,000 Turkish citizens. The members of these covert ISIS networks represent a key threat to Turkey’s internal security, and ISIS will likely seek to activate these cells in order to punish the Turkish government. ISIS fighters and supporters began circulating violent rhetoric against the Turkey within hours of the Turkish airstrikes on July 24. At the same time, Turkey also faces expanded internal turmoil in its southeastern Kurdish-majority provinces due to the resumption of hostilities with the PKK and other Kurdish militant groups. These two simultaneous threat streams will likely interact to prompt further attacks inside of Turkey in coming weeks targeting the Turkish government, Turkish military forces, or vital Turkish interests such as the tourism industry.

Turkish intervention in Aleppo Province could also prompt a response from Syrian al-Qaeda affiliate Jabhat al-Nusra (JN) and JN-aligned Salafi-jihadist groups operating along the Turkish border. Unverified Turkish sources identified both ISIS and JN as targets for Turkish and U.S.-led coalition airstrikes. JN later claimed on July 24 that aircraft from the “Arab-Crusader alliance” had conducted airstrikes against JN positions in the town of Baraghitah in northern Aleppo Province. Baraghitah is located directly adjacent to the announced location of Turkish airstrikes in the town of Hawar Kilis, suggesting that Turkish aircraft may have also conducted strikes against JN. Although JN remains unlikely to directly escalate against Turkey due to its own reliance on supply lines running through the Turkish border, sustained targeting of JN could ultimately drive the group to conduct attacks against Turkey or Turkish-sponsored rebel groups operating in Aleppo and Idlib Provinces.

Meanwhile, Turkish military action against ISIS forces in northern Syria could produce significant ramifications for the current balance of power between ISIS, Syrian rebels, and the Syrian regime in Aleppo Province. A sustained campaign of Turkish airstrikes and artillery shelling designed to force ISIS away from the Turkish border would likely open exploitable opportunities for rebel forces to advance against ISIS in the northern countryside of Aleppo City, reversing ISIS’s recent gains in the region and reducing the threat posed to the key rebel supply line moving from Turkey through the Syrian border town of Azaz. Over the long-term, ISIS’s position could be sufficiently weakened to enable advances by both rebel and regime forces east of Aleppo City, which could ultimately threaten ISIS’s control over the key urban centers of al-Bab, Manbij, and Jarabulus. Turkey will also likely seek to leverage these rebel advances as a means to block further Syrian Kurdish advances in Aleppo Province along the Turkish border. On a wider scale, the campaign of mass arrests and invigorated border security efforts undertaken by the Turkish government could result in a significant disruption of the foreign fighter flows which provide ISIS with a key source of reinforcements, suicide bombers, and legitimacy as a global caliphate. The intersection of these effects with potential losses of terrain in Aleppo Province would likely inflict significant damage to ISIS’s operations within both Iraq and Syria. ISIS may thus attempt to reduce its overall risk profile by setting conditions over the near-term to secure additional border access, particularly in the opposition-held province of Idlib in northwestern Syria which has seen a series of recent ISIS-attributed assassinations and bombings.

The increase in Turkish support to the U.S.-led anti-ISIS coalition through expanded border security, airstrikes, and airbase access will deliver an immediate boost to U.S. efforts to degrade and defeat ISIS in Iraq and Syria. Nonetheless, Turkey’s decision to escalate against both ISIS and the PKK will also produce a number of challenges for the U.S. and its coalition allies in the near-term. The high likelihood of retaliatory attacks in Turkey directed by both Salafi-jihadist and Kurdish militants suggests that the U.S. will witness persistent violence in a major NATO ally. U.S.-led coalition personnel stationed at newly-opened airbases in Turkey may come under particular risk of attack due to the heavy presence of ISIS networks in the country. The U.S.-led coalition could also face pushback or reduced cooperation from the Syrian Kurdish forces that have formed the core U.S. ground partner in Syria as a result of renewed hostilities between the Turkish government and the PKK. Over the long-term, however, the expansion of the Turkish role against ISIS will likely mark a major positive development for the U.S.-led anti-ISIS coalition and its efforts to dismantle the Islamic State.

Christopher Kozak is a Syria Analyst at the Institute for the Study of War.