TURKEY’S CHANGING SECURITY ENVIRONMENT AND TRANSFORMATION OF TURKISH FOREIGN POLICY

Turkiye’nin 1990’lardaki guvenlik odakli dis politikasi 2000’li yillarda Turk dis politikasinin Avrupalilasmasi olarak da nitelendirilebilen daha liberal yonde bir degisim gecirmistir. Ancak bu dis politika, 2010’larda sert guce basvurulmasiyla yeniden guvenliklestirme surecine yonelmistir. Bu makale soz konusu yonelimi, Turkiye’ye yonelik ic ve dis tehditlerin yogunlugundaki degisimi analiz ederek incelemeyi amaclamaktadir. Bu analizde temel olarak, Suriye’de devam eden ve Turkiye’deki PKK terorunun yeniden ortaya cikisina olanak saglayan ic savas ve DAEŞ’in terorist saldirilari uzerinde durulacaktir. Sonuc olarak, Turkiye’nin guney dogu sinirini cevreleyen istikrarsiz siyaset ve guvenlik ortami, ulusal dis politikada sert gucun kullanilmasina yol acmistir. Onceki on yilin aksine, ulke ici ve sinir otesi teror tehditlerine karsi askeri guc kullanimi, ulusal guvenlik cikarlari acisindan kacinilmaz hale gelmistir.


INTRODUCTION
Since the 2010s, Turkey's national foreign policy has been dramatically transformed into a security-oriented one that once more resorts to hard power and coercive diplomacy. 1 Although such a security-centred approach had dominated Turkish foreign policy throughout the 1990s, there was a dramatic shift in the 2000s towards more cooperative, liberal policies, which was termed as "Europeanization" as well. Throughout the 1990s, Turkey's relations with neighbouring states, including Iraq, Iran, Syria and Greece, significantly deteriorated due to their support for the terrorist Kurdish Workers Party (Partiya Karkerên Kurdistan -PKK) that endangered the country's territorial integrity. This led Turkish governments to confront neighbouring states with military measures and coercive diplomacy. However, starting in the mid-2000s, the "zero problem with neighbours" foreign policy of Turkey's ruling Justice and Development Party (Adalet ve Kalkınma Partisi -AK Party) and the European Union's (EU) push for a more liberal foreign policy led to the Europeanization and de-securitization of Turkish foreign policy, which promoted interstate cooperation and soft power. During this period, Ankara attempted to establish peaceful and harmonious relations with its neighbours. Yet, by the beginning of the 2010s, Turkish foreign policy had drastically shifted away from Europeanization and transformed its liberal policies back to security-oriented policies (Oğuzlu, 2016). This article analyses this reversal in Turkish foreign policy by examining the changes in the intensity of internal and external threats to Turkey through a realist and liberal foreign policy analysis. To do so it concentrates on the civil war in Syria, which 1 In the international relations discipline, the concept of coercive diplomacy is used to define an act of coercion where a state aims at convincing the other side to stop or undo an already ongoing action that is not desired by the state resorting to coercion. By definition, the state resorting to coercion threatens the target with the use of hard power mostly, however, not solely in terms of military force, or with the actual use of it only in a limited scale (Jakobsen, 1998;Berridge & James, 2003). Within this framework, hard power refers to a state's ability to influence another state's actions through coercion with tangible factors including the use of its armed forces (Nye, 2016). had a considerable impact on the increase in PKK terror as well as attacks from terrorist group Islamic State of Iraq and Syria (ISIS), which put Turkish citizens in danger.
The article starts with a theoretical background that explains the theories of foreign policy analysis that helps us to analyse the transformation in Turkish foreign policy from a realist one in the 1990s to a liberal foreign policy in the 2000s and then back to realist foreign policy in the 2010s. To do so, the section will concentrate on the realist vs liberal analysis of foreign policy as well as Europeanization and de-Europeanization of foreign policies in the same context. Then the article will continue with a brief analysis of the 1990s' realist securitybased Turkish foreign policy and its Europeanization in the 2000s by moving towards a more liberal and cooperative soft power phase. The following section analyses its reversal back to re-securitization again by resorting to realist analysis. The article is concluded with an analysis of the dynamics and factors that led to this reversal.

THEORETICAL FRAMEWORK: TRANSFORMATION FROM REALISM TO LIBERALISM AND BACK TO REALISM
Foreign policy analysis aims at bringing theoretically informed explanations to the factors that shape foreign policy decisions. In one of the most significant contributions to the literature, Juliet Kaarbo et al. (2013) classify various factors into two wide categories that are the international and the domestic environment. To analyse the impact of international system they benefit from the explanatory power of the theories of international relations including realism and alternates of liberalism and constructivism.
Realist theory considers anarchy and conflict as the main characteristics of international system since there is no overall international legal order that actors can follow. According to realist argument, without a global police, states try to maximize their interests to protect themselves and survive in world politics. Stronger and aggressive neighbours create a serious threat for these states. States are in a constant need to attain and defend their own security and power (Kaarbo et al., 2013: 7-8).
Similarly, as will be analysed in the next section, Turkish foreign policy during the 1990s was in a constant need to protect its interests in a new post-Cold War environment in which the bipolar international system ended and its alliance with the United States (U.S.) was not that significant anymore. Although in this new system Turkish foreign policy-makers had more area to manoeuvre, they also had more threatening neighbours that they had to deal with due to the new conflicts in the Balkans and the Middle East.
While realism has a significant explanatory power to analyse the foreign policies of the states, it excessively concentrates on military conflict without taking economic cooperation into consideration. Thus, security interests do not always guide the foreign policies of the states. A country may establish good relations with its neighbours through economic engagements. Economic power and economic cooperation can lead the foreign policies of the countries as liberalism explains (Kaarbo et al., 2013). Keohane and Nye (1989: 24-27) argue that military security is not the only priority of foreign policy-makers. In case of anarchy states do not always use their military power but their economic power which can also be identified as soft power.
The use of soft power and economic cooperation as analysed under the section titled "De-securitized Foreign Policy of the 2000s: Europeanization and Domestic Dynamics", dominated Turkish foreign policy throughout the 2000s. During this period, security-oriented policies were replaced by economy-oriented policies and a complex interdependence between Turkey and its neighbours was established. Such an interdependence as defined by Keohane and Nye (1989: 24-27) increased the use of numerous networks for interaction between states and weakened the dominance of military force.
This complex interdependence went hand in hand with the Europeanization of Turkish foreign policy in which the EU's involvement in Turkey's domestic and foreign policies were taken into consideration by the Turkish foreign policy-makers due to Turkey's candidacy status. However, this economy-oriented foreign policy started declining as a result of the instigation of the civil war in Syria in 2011 when Turkey started facing terror attacks from different fronts including PKK and ISIS. Therefore, in line with the realist theory, Turkey began to react to potential threats in 2010s by resorting to hard power in order to protect its territorial integrity.

TURKEY'S SECURITY-ORIENTED FOREIGN POLICY OF THE 1990s
The end of the bipolar international system in the 1990s gave Ankara greater autonomy as a regional power. The conflicts of this period, particularly in the Balkans, in addition to Turkey's problems with Syria, Iraq, Iran and Greece concerning their support to PKK, led to the expansion of the Turkish military's traditional autonomy over foreign policy decisions. The rise of Kurdish nationalism that was associated with violent PKK attacks on both the Turkish military and civilians boosted security concerns. Given this highly insecure environment, Turkey adopted a security-centred foreign policy and resorted to coercive diplomacy (Renda, 2011: 93-94). During this period, Syria and Greece did not refrain from hosting the terrorist PKK leader whereas Iraq and Iran did not show consent for joint cooperation in Turkey's struggle against separatist terrorism. Moreover, Greece used its veto right against Turkey's EU candidacy.
By providing arms to PKK militants as well as training them in camps, the Syrian government used the Kurdish problem as leverage against Turkey in the long-lasting dispute over the distribution of water between two countries. 2 In 1998, the Turkish government considered declaring war against Syria to achieve the deportation of terrorist PKK leader. In addition, PKK attacks on Turkey from across the Iraqi border increased due to the power vacuum in Baghdad following Saddam Hussein's defeat. Formation of the no-flight zone across Turkey's borders also provided a haven for PKK members to establish bases across the border from which to launch attacks against Turkey. To crush these militants and wipe out terrorist cells, the Turkish military conducted a series of cross-border operations in Iraq (Kirişci, 2004: 283). Meanwhile, Iran's attempts to change the regional balance of power since the revolution in 1979 by interfering in its neighbours' domestic politics to export Islamist revolution was not welcomed by Turkey. These ideological differences led to antagonism between the two countries that ranged from minor disputes between politicians to Iranian support for religious fundamentalist groups and PKK militants (McCurdy, 2008: 88).
Along the same line Turkish foreign policy makers experienced tense relations with their European neighbour Greece. All of these relations with the neighbours enhanced the understanding that Turkey is surrounded by hostile countries. In this context, Turkish-Greek relations, that were shaped by historical enmities and long-lasting conflicts, including the Cyprus crisis, the extension of Greek territorial waters, airspace control, the continental shelf, remilitarization of Eastern Aegean islands and disputed islets, continued following a similar negative path throughout the 1990s. Moreover, during this period, the two countries came to the brink of war due to a row over the sovereignty of uninhabited islets in the Aegean (Heraclides, 2010).
As realism argues, during the 1990s, Turkish governments were in a constant need to achieve and guard Turkey's national security and power. There were threats coming from majority of the neighbouring countries due their support to PKK terrorism that had constantly been endangering the territorial integrity of Turkey and security of Turkish society.

DE-SECURITIZED FOREIGN POLICY OF THE 2000s: EUROPEANIZATION AND DOMESTIC DYNAMICS
Beginning by the 2000s, Turkish governments abandoned its securitybased foreign policies and began following more liberal and cooperative foreign policies to resolve their conflicts through soft power. Starting with Turkey's EU candidacy in 1999, being followed by the country's economic crises of 2000 and 2001, national foreign policy entered a phase of economic liberalization, based on commerce, cooperation and soft power. As Renda (2011: 90) puts it, in the 2000s, an "economy-oriented 'new activism' has prevailed over the security-first activism of the 1990s".
The conflict-ridden relations between Turkey and Syria during the 1990s were transformed into political, social and economic cooperation following the 1998 Adana Accords and PKK leader Öcalan's deportation from Syria. In the immediate aftermath, Syrian President Bashar al-Assad, sent his Vice-President to Ankara with a message about making a fresh start on Syrian-Turkish relations. This was followed by removal of landmines between two countries' adjacent territories in 2002 (Mufti, 2002). The Turkish government defended the Assad regime against the U.S. economic sanctions in May 2004 (Kuru, 2012). Both parties decided to establish a Strategic Cooperation Council in September 2009 and signed around 50 agreements and many memoranda of understandings that emphasized cooperation on politics, security, commerce, water, transportation, education, health, culture, agriculture and environment. Turkish foreign policy-makers also started the mediation policy between Syria and Israel during 2008 (Baç & Gürsoy, 2009: 421;Bishku, 2012).
Turkey's relations with Iraq improved when Ankara allied with Germany and France against the U.S. led invasion in 2003. Turkish Grand National Assembly did not allow U.S. military forces to reach Northern Iraq over the country's south-eastern border. Turkey and Iraq then started cooperating against the common threat of PKK terror. Despite Ankara's uneasiness over Iraq's Kurdish nationalist movements, Turkish policy-makers gradually accepted the federal structure in Iraq and established economic ties between the Kurdish Regional Government (KRG) and Turkey's public and private sectors. In his visit to Iraq and meeting with Iraqi President Jalal Talabani in July 2008, Prime Minister Erdoğan signed a strategic partnership agreement that included regular meetings between government leaders and state officials in addition to establishing a high council. High-level visits concerning cooperation in the fight with terror continued with both the Bagdad government and KRG President Massoud Barzani between 2008 and 2010. Furthermore, AK Party's policy-makers involved Barzani in the "democratic opening process" in 2012 that aimed to settle Turkey's Kurdish question (Pusane, 2016: 23). Turkish companies made a series of investments, particularly in Iraq's Kurdish region, by building Erbil's international airport, the U.S. Embassy, Sulaymaniyah Airport and many highways. In 2010, trade between the two countries reached $ 6 billion (Kirişçi, 2006).
Turkey and Iran abandoned their ideological differences and moved towards a more cooperative phase concerning the economy, energy security and the joint struggle against international terrorism. As Iran was suffering from terror attacks by the Kurdistan Free Life Party (Partiya Jiyana Azad a Kurdistanê -PJAK) following the 2003 American invasion of Iraq, it cooperated with Turkey against the increasing autonomy of Kurds in Iraq (Karacasulu & Aşkar-Karakır, 2011: 111-119). 3 Turkey and Iran signed a joint memorandum as well. Both capitals decided to act together in their fight against the PJAK and PKK in April 2008, following the 12 th High Security Commission meeting (Sadık, 2008). The Turkish government reacted to the U.S. government's move to isolate Iran regionally and defended Tehran's possession of nuclear power for peaceful aims by complying with the rules of the International Atomic Energy Agency. In 2010, Turkey played an important role along with Brazil in Tehran's signing of a nuclear exchange agreement. By signing the Nuclear Non-Proliferation Treaty (NPT), Turkey also supported EU efforts to prevent Iran's development of nuclear weapons. In 2001, the Tabriz-Erzurum pipeline started carrying Iranian gas to Turkey. By the late 2000s, Turkish manufactured good exports to Iran amounted to $2 billion while Iranian natural gas exports to Turkey amounted to $8 billion. Throughout the 2000s, Turkey and Iran established economic cooperation by abandoning their previous security-dependent relations (Karacasulu & Aşkar-Karakır, 2011: 115-116).
Turkish-Greek relations, which had begun to improve by the end of 1990s became part of Turkey's EU accession agenda by the early 2000s following Athens' policy change towards Turkey's EU perspective. Greece decided to upload Turkish-Greek bilateral disputes to the EU level and benefit from the asymmetrical power relationship between the EU and candidate states. In addition, the capture of PKK leader Öcalan, hiding in the Greek Embassy in February 1999, is considered as another factor that forced Greece to change its strategy of blocking Turkey's EU candidacy. During this period, Ankara and Athens showed signs of progress in bilateral relations including the signing of cooperation agreements on terrorism, environment, tourism and energy transportation. Moreover as Ker-Lindsay (2000) notes, the devastating Marmara earthquake of 1999 in Turkey created cooperation between citizens of the neighbouring countries as well.
Following the 1999 decision of the EU to recognize Ankara's candidacy status, EU leaders underlined a need to resolve bilateral disputes between the two countries, along with the Cyprus dispute (European Council, 2004;European Commission, 2005). In the post-Helsinki period, the EU also contributed to improving relations by encouraging both sides to cooperate in several fields (Aydın & Açıkmeşe, 2007). Concerning the Cyprus question, in conformity with the EU's agenda, Ankara advocated the UN's initiative for a single federal state solution. In spite of Turkish Cypriots approval of the Annan Plan, the Greek Cypriots' refusal in 2004 led to its failure (Smith, 2004). In mid-2005, although Turkish government extended the Customs Union Agreement for the inclusion of EU's newcomers of the time, it opposed granting Greek Cypriot vessels access to Turkey due to lack of the existence of a formal recognition. Turkey's failure to apply the Customs Union's requirements inclusive of Greek Cypriots, led to the suspension of 8 negotiating chapters in 2006, which delayed Ankara's accession process with Brussels (Batalla, 2017).
As liberalism points out, during this period, Turkish governments by prioritizing economic cooperation with their neighbouring countries established a complex interdependence. By doing so they resorted to use of soft power in their foreign policy. This shift towards the use of soft power during the 1990s via liberal and cooperative approaches in Turkish foreign policy emanated from two significant dynamics: the EU conditionality on Turkish foreign policy, which can also be termed as Europeanization; and changes in Turkey's domestic political structure.

Europeanization of Turkish Foreign Policy
Europeanization is a theoretical concept generally used for analysing changes in the EU member states. Nevertheless, it is also used for explaining policy shifts in candidate states. Europeanization can take place in two ways. The first is through formal EU decisions and its adoption by candidates. The second is through interactions between the EU and domestic level (Baç & Gürsoy, 2009: 405-407). In the Turkish case, the 'top-down' approach was chosen due to Turkey's candidacy status. The EU's involvement in Turkey's domestic and foreign policies, has enabled the national political environment to be receptive of the EU's conditionality strategy. The EU conditionality on Turkish foreign policy, which was made official in the 1999 Helsinki European Council's Presidency Conclusions, defined the general framework for candidate states' policies in dealing with their border disputes. The document stated that the European Council requires candidate states to resolve their disputes through peaceful settlement according to the UN Charter. 4 During the accession negotiations, Ankara adopted reforms to meet the Union's political criteria. Most significant among these took place in civil-military relations which led to the subordination of the military to the civilians. This included reduction of National Security Council's power and the increase in the number of civilian members in the Council. In fact, the decrease in the Turkish Armed Forces' involvement in politics also stimulated the increase in diplomatic initiatives and the abandonment of military instruments. This has led to a process where economic relations found a fertile ground to flourish. Both countries have increased their bilateral trade numbers. Aligning with EU norms, the Turkish government and the civilians took over the leadership role on foreign policy issues. During the 2000s, Ankara's military-focused security culture, which had been mostly based on threat perceptions, was displaced by an emphasis on cooperation. This showed itself in increasing bilateral contacts and economic engagements in foreign policy cases, particularly with neighbouring countries, including Greece, Syria, Iraq and Iran (Baç & Gürsoy, 2009: 415-416).

Domestic Context and its Impact on Foreign Policy
Besides Europeanization, AK Party governments introduced distinct changes to the conduct of national foreign policy throughout the 2000s. Turkish policy makers focused on Turkey's involvement in far geographies and revealing common cultural affinities (Davutoğlu, 2001). It was aimed at making Turkey a full EU member by promoting a regional environment of security, stability, prosperity and cooperation. Moreover, as could be observed in its relations with Iraq, Iran, Syria and Greece, Ankara aimed at minimizing problems, establishing trust and promoting economic and political cooperation. By doing so, Turkey managed to raise its status as an influential regional power with a global perspective. Successive AK Party governments attempted to influence politics in the Middle East by mediating between Israeli and Syrian governments along with significant attempts to resolve the Gaza crises of 2007(Aras, 2009. Turkey followed this multi-dimensional foreign policy by maintaining strategic relations with the U.S. through bilateral ties and NATO, pursuing full EU membership, establishing a good neighbourhood policy with Russia, and adopting a synchronization policy in Eurasia. Turkey also used rhythmic diplomacy by hosting a NATO Summit and an Organization of Islamic Communities Foreign Ministerial Meeting in İstanbul in 2004. It became affiliated with several regional institutions. 5 Turkey had become an active G-20 member (Aras, 2009: 134;Davutoğlu, 2008: 82-83). Besides the government, civil society organizations, lobbied to facilitate Turkey's EU perspective. Representatives of the business sector was actively involved in organizing business meetings with counterparts from different regions. Following the 2005 earthquakes in Pakistan and the tsunami in the Indian Ocean, Turkish civil society organizations influenced Turkish foreign policy through their aid programmes (Davutoğlu, 2008: 83-84).
In sum, compared to the post-Cold War foreign policy of the 1990s, Turkey's military lost its dominant power over foreign policy-making. Throughout the 2000s, Ankara's foreign policy vision reflected signs of Europeanization by aiming to respect civil rights while protecting security, settle disputes peacefully, engage in international organizations, and emphasize good neighbourly relations and diplomacy. During the 2000s, Turkish foreign policy moved into a conciliatory phase by making use of economic and diplomatic tools in its relations with Iraq, Iran, Syria and Greece.

RESECURITIZATION OF FOREIGN POLICY DURING THE 2010s
Turkey's de-securitized foreign policy using diplomatic and economic tools during the 2000s, returned to its realist and security-oriented form during early 2010s. Ankara reached the limits of diplomacy and economy oriented power capabilities in its region (Aras, 2014: 404). The commencement of the Arab Spring in 2010, followed by the civil war in Syria in 2011, gradually reversed Turkish foreign policy to its 1990s hard power and security-first approach. Increasing PKK terror due to the political vacuum in Syria as well as ISIS attacks against Turkish citizens due to Ankara's backing of the Free Syrian Army led to a rapid deterioration in the country's ties with the Syrian government.
The main turning point towards securitization was the transformation of the uprising in Syria into a civil war in the early 2010s. The shared 900-km border increased Turkey's security concerns related to revived PKK terror and attacks by ISIS members entering the country alongside millions of Syrian citizens seeking refuge (Ayata, 2014: 95-96). Initially, Turkey had tried to persuade Syrian President Bashar Assad to stop his brutal crackdown on protesters and implement political reforms. However, when these efforts did not work, the Turkish government started hosting the Syrian opposition in Turkey. In late 2012 Assad withdrew his forces from northern Syria, which allowed Syrian Kurds to occupy Jazira, Kobani and Afrin. Meanwhile, Syrians, among whom PKK and ISIS militants hid, started fleeing to Turkey.
Turkish policy-makers, underestimating Russian and Iranian support for Assad, expected the Syrian regime to rapidly collapse. Moreover, Ankara's choice for standing behind the Syrian opposition hampered Turkish-Iranian cooperation. Turkey's efforts to support an EU drafted UN resolution in October 2011 condemning Syria's government and imposing sanctions failed due to the Russian and Chinese vetoes (Ayata, 2014: 103). Relations between the Syrian government and Turkey worsened further with the shooting down of a Turkish military fighter in June 2012 and the Syrian mortar bomb attack in June 2012 which killed 5 citizens in Turkish town of Akçakale. The killing of more than 52 people by terrorist bombing attacks in Reyhanlı in May 2013 further increased Turkey's security concerns (Fahim & Arsu, 2013;Hürriyet Daily News, 2012;Russia Today, 2013).
In the following years, the civil war in Syria substantially damaged Turkey's security and economy. By 2019, the number of officially registered Syrian migrants in Turkey reached to 3.6 million. Although Turkey has supported the opposition to Assad, some groups within it, such as the Kurdish Democratic Union Party (PYD) and its armed wing, the People's Protection Units (YPG) allied with the PKK in its separatist terror acts. Turkey's war with Kurdish groups in Syria jeopardized its relations with the U.S., which has supported PYD and YPG against ISIS.
From August 2016 until March 2017, Turkey implemented the Operation Euphrates Shield in response to the terrorist attacks of ISIS and PKK/YPG. The operation can be evaluated in terms of Turkey's changing security environment and increasing threats caused by ISIS and PKK/YPG in northern Syria adjacent to the Turkish border line. Ankara's decision to militarily involve in an operation in the Syrian territory was in line with Article 51 of the UN Charter that gives its member states the right of self-defence (Yeşiltaş et al., 2017). In January 2018, Ankara initiated the Operation Olive Branch together with the Free Syrian Army against ISIS and PKK/YPG in Afrin of Syria. The military operation phase took two months to expel terrorists out of the city (TRT World, 2018).
Turkey's relations with Iraq also started to decline again due to the PKK and ISIS attacks on Turkey. In the mid-2010s, ending its five-year unilateral ceasefire, the PKK re-started attacks in rural and urban Turkey (Jenkins, 2010). When Turkey's "democratic opening process", was hampered in 2015 due to continued PKK attacks, the Turkish government re-launched its fight against separatist terrorism by bombing its installations in Iraq. These attacks had side effects on the fragile partnership between Turkey and KRG. Turkish government and Barzani in northern Iraq allied against the PYD control in north Syria and opposed initiatives of PYD's autonomous status in 2013. Later, however, ISIS attacks led the YPG, PKK and KRG to ally leading to the deterioration of Turkish-KRG relations (Kayhan-Pusane, 2016: 24-26).
Another conflict between Turkey and Iraq arose from the arrival of 500 Turkish troops in Bashiqa on the invitation of local forces, but not the Baghdad government, in 2015 to help train Iraqi militias in the fight against ISIS (İdiz, 2017). Accusations between the Nouri al-Maliki government of Baghdad and Ankara of following sectarian policies created tensions between the two countries in the early 2010s. 6 In October 2015, another similar tension took place concerning discussions on the population structure in Mosul and Tal Afar after the liberation of these areas from ISIS. More positively, this conflict ended with Erdoğan's friendly phone conversation with Prime Minister Haider al-Abadi in December 2015 and later on it was followed by joint cooperation against ISIS and PKK (İdiz, 2017). In addition, the two governments allied against KRG President Barzani's declaration of Kurdish independence following a KRG referendum in September 2017 (Al-Monitor, 2017).
Problematic Turkish-Iranian relations also worsened in the early 2010s when the two countries took opposing positions in Syria's civil war. While the Turkish government supported anti-Assad groups, Iran and Russia backed the Assad regime. Concerning sectarian conflicts in Iraq, Turkish-Iranian relations were again at odds since Turkey claimed that it was its duty to look after Iraq's Sunni and Turkmen population considering the ISIS threat and other hostile groups. Tehran, however, viewed Ankara's decision to protect Sunnis as an incursion. After a power vacuum emerged along Turkey's south-eastern border due to ISIS' loss of control over a large area, another struggle between the two countries started. While Turkey did not want Iran-backed militias, Assad's forces or the YPG to take over these territories close to its borders, Iran did not want a Turkish military presence in Iraq or Syria. When the Turkish government accused Iran of Persian expansion in the region during the summer of 2017, the Iranian government expressed its uneasiness with Turkey's Euphrates Shield Operation along with the Afrin Operation that has started in January 2018 (Bora, 2017;Jones, 2017).
Nevertheless, despite these conflicts, Turkish-Iranian economic relations continued as usual since Ankara was the major buyer of Tehran's natural gas. The Iraqi Kurds' independence referendum of September 2017 also brought the two sides together since they were both against the establishment of an independent entity due to the possibility of a snowball effect for their own Kurdish populations. 7 In November 2017, Turkey, Iran and Russia met at the Black Sea resort of Sochi with the aim of ending the war in Syria and leaving Assad in power under a reformed Syrian constitution. This development can be interpreted as reflection of the convergence of concerns and threat perceptions because both countries had otherwise diverging interests in both Iraq and Syria (Jones, 2017;Wintour, 2017). 6 While the Turkish government accused the Baghdad regime of following sectarian, pro-Shia policies, the Baghdad government accused the Turkish regime of following pro-Sunni policies. See Kuru, 'Turkey, Iran and Sunni-Shiite Tension'. 7 Although both Turkey and Iran are worried about the establishment of an independent Kurdistan, Turkey prefers to minimize the PKK-PYD threat and is ready to tolerate Iraq's Kurdistan Democratic Party (KDP), whereas Iran would not tolerate the establishment of an independent Kurdistan in Iraq.
Regarding Turkish-Greek relations, despite an increase in high level visits, commercial and economic relations, and new agreements, protocols and memoranda from meetings of the High-Level Cooperation Council, tensions are still running high (Bechev, 2017). Nevertheless, certain joint projects, such as the construction of Trans Adriatic Pipeline to ship Caspian gas pumped through the Trans Anatolian Pipeline that will cross through Greece and Albania, are still under way. There are also plans to renovate the railway connection between İstanbul and Thessaloniki and establish a regular ferry route between İzmir and Thessaloniki (Bechev, 2017). However, there have also been increasing airspace violations and a resumed power struggle in the Aegean Sea, the failure to resolve the Cyprus conflict and problems created by refugee flows between the two countries (The Economist, 2017). President Erdoğan's visit to Greece in December 2017 seemed to be a historic moment as he was the first Turkish President to do so since 1952. However, debates around the Lausanne Treaty and the return of Turkish citizen fugitives who found shelter in Greece after the July 2016 terrorist coup attempt of Fethullah Gülen Terrorist Organization (FETO) overshadowed the visit. When the Greek Supreme Court rejected Turkey's request to extradite them, tensions due to existing disputes received more attention . In January 2017, both countries' warships had a minor confrontation in the Aegean due to disagreements over sovereignty rights (The Guardian, 2017).
We explained Turkey's shift towards soft power during the 2000s through liberal and cooperative approaches in relation with Europeanization approach and changes in the domestic political structure. Similarly, the re-securitization of national foreign policy can be analysed in terms of de-Europeanization and changes in the domestic political structure. However, neither explanation is sufficient to account for developments without analysing the changing intensity of three specific threats: first PKK terror, second ISIS attacks and third coup attempt of FETO.

De-Europeanization
During the 2010s, Turkey's liberal, soft power foreign policy was replaced by a security-oriented one. The EU started to lose its impact, not only on Turkey's foreign policy, but also on its domestic policies as well. Due to the changing security environment, Turkish governments faced a trade-off between prioritizing traditional security concerns and maintaining good neighbourly relations. As discussed earlier, the regional power vacuum created by the Syrian conflict caused a rapid deterioration of Ankara's relations with Syria, Iraq and Iran. The weakening of relations also showed itself, albeit in different ways, with Greece specifically and European countries generally. In the insecure environment due to the civil war in Syria, which enabled PKK and ISIS attacks on Turkey, it was no longer possible to utilize soft power for maintaining security and minimizing threats.
According to Ovalı (2012: 142-143), a significant factor influencing the Turkish government's political choice to move away from Europeanization to de-Europeanization was the Turkish political elites' increasing self-confidence over the country's relative success during the 2008 global financial crisis. Such confidence and the negative attitudes of European leaders towards Ankara's accession path also led the governing elites seek alternatives to EU membership based on regional integration (Özek & Oğuzlu, 2013: 695-696). As Jorgensen notes (2016: 118), during the post-2005 period the lack of a credible accession prospect led Turkey to lose its enthusiasm concerning Europeanization efforts. The lack of enthusiasm enhanced de-Europeanization tendencies in Turkey's domestic and foreign policies. This weakened the EU's capacity to influence Turkish society and politics while societal scepticism of and indifference towards the EU and the legitimacy of EU-led reforms increased immensely (Aydın-Düzgit & Kaliber, 2016: 5-6). Chapter 31 of the EU Commission's 2016 Progress Report on Turkey that focuses on foreign, security and defence policy, stated that Ankara had shown alignment with 18 out 41 EU declarations and Council decisions, indicating 44% alignment concerning the Union's common foreign policy (European Commission, 2016). These statistics reflect the divergence particularly with the results of previous years.
Moreover, the EU's reluctance in approaching the humanitarian tragedy associated with the Syrian refugee crisis further diminished its transformative capacity in Turkish politics. The EU member states' inability to prioritize human dignity and defend democratic values during the refugee influx towards Europe have ended up with negative side effects on its normative reputation in Turkey (Öniş & Kutlay, 2017). The refugee crisis also created ample space for nationalist European politicians to follow populist discourses and disregard European values.
In fact, the de-Europeanization process had not only taken place in Turkey. The rise of Euro-sceptic far-right parties in Europe led to the de-Europeanization policies in some EU member countries as well. Increasing public support for rightwing extremists in several member states along with Austrian, French and German opposition to Turkey's EU membership have deteriorated EU-Turkish relations. Many European political figures benefit from a heavily critical discourse towards Turkey's candidacy to attract popular support from their constituencies within an increasingly populist political environment (Kardaş, 2009). The resultant growing discontent of Turkish political leaders in line with declining popular support from Turkey's public for the EU membership all greatly reduced the EU's capacity to influence Turkish foreign policy. Thus, Turkish-EU relations returned to mutual scepticism and prejudice rather than cooperation (Keyman, 2017;Özek & Oğuzlu, 2013). Therefore, Turkey's de-Europeanization process can hardly be explained by solely focusing on the country's domestic developments. The shifting tendencies of the EU member states' national politics hindered European leaders' potential support for Turkey's accession which strictly limited the projection of the EU's transformative power.

Changes in the Domestic and International Contexts
Although de-Europeanization had some considerable role in shifting Turkish foreign policy from a de-securitized to securitized form, the change in the domestic context, that took place due to changes in the security environment forced Ankara to return to a security-oriented foreign policy. In this context, realism brings a significant explanation to Turkey's re-securitized foreign policy with the increasing threat coming from the neighbouring states. The initiation of civil war in Syria changed the whole security atmosphere for Turkey leading to an insecure neighbourhood. The establishment of illegitimate autonomous regions in Syria near Turkey's border forced the Turkish Armed Forces to take precautions to defend the country from terror attacks. In supporting separatist Syrian Kurdish groups in the fight against ISIS, neither the U.S. administration nor Russian policy-makers were concerned about protecting Turkish regional interests (Gürcan, 2017). Whereas Turkey was acting as a regional actor promoting political liberalization in Syria and other parts of the Middle East in 2010, by 2017 it was militarily involved in the Syrian turmoil created by other regional and global players, as well as many radical terrorist groups (Ayata, 2014: 104-105).
During this period, the number of PKK and ISIS attacks rose dramatically. The PKK abandoned a five-year unilateral ceasefire to revive its rural insurgency in the mountains of southeast Turkey in addition to an urban bombing campaign in the western part of the country. Although the PKK announced the suspension of all offensive operations during indirect negotiations with the Turkish state in April 2009, it continued its attacks in rural areas in the southeast at a lower level (Jenkins, 2010). In 2015, by killing several policemen and soldiers, and attacking military posts, PKK jeopardized the fragile democratization process. Meanwhile, more than 400 civilians, including governors, politicians, workers and teachers, have been killed and more than 2.000 people have been injured in PKK attacks across Turkey in mid 2010s. The organization also planted bombs in residential areas, mosques and schools (Okur, 2017). From early 2014 until early 2017, there were more than 20 ISIS attacks. The number rose before the June 2015 general elections and continued after the elections, mainly in eastern Turkey, particularly in Gaziantep as well as major cities, including Ankara and İstanbul. These attacks killed more than 200 people and injured hundreds of them (Al Jazeera, 2017).
Consequently, the Turkish government re-launched its fight against the PKK as well as ISIS. Turkey's attacks against PKK, put the Turkish-KRG partnership in danger in the light of KRG President Barzani's alliance with the PKK/PYD against ISIS. Although Barzani's KDP and the PKK/PYD are allies in their fight against ISIS, there are still tensions among them. The KRG heavily needs the pipeline infrastructure between Kirkuk and Yumurtalık, making Turkey its main economic gateway to the outside world (Kayhan-Pusane, 2016: 25-26). However, Turkey still has to be careful about its fragile relations with Iraq as these have fluctuated widely due to the sectarian disputes between the two countries.
Turkish-Iranian relations reached a stalemate when Turkey supported the opposition to the Assad government whereas Iran allied with Assad in the Syrian civil war. Turkey does not want to see an Iran-backed militia along its borders to fill the power vacuum created by ISIS' loss of large pieces of territory. While Iran has acted as the guardian of Iraqi Shias, Turkey has attempted to do the same for Iraqi Sunnis. In fact, there have been some signs of cooperation since both oppose the PYD/YPG gaining power. Moreover, they held a meeting with Russia in Sochi to end the turmoil in Syria. Nevertheless, Iran and Turkey's interests concerning Iraq and Syria differ significantly.
Unlike the period of Europeanization during the 1999-2005 period, Turkish-Greek relations have faced more tensions, including violations in the airspace, the power struggle in the Aegean Sea, the Greek Cypriot Administration's blocking of EU-Turkish negotiation chapters, the refugee crises and the dispute over the delimitation of Eastern Mediterranean maritime areas. Turkey and Greece have diverging views towards exploration and sharing of potential energy resources in the region around the Cyprus Island. Since 2011, significant off shore natural gas reserves have been discovered in the Eastern Mediterranean following the Greek Cypriots' initiatives for exploration around the island. While this move undermines Turkish Cypriots' sovereign rights, attempts for the discovery of resources are continuing in a way that excludes Turkey as well. This has led to disagreements over the Exclusive Economic Zones (EEZ) and urged Ankara to increase Turkey's military presence in the Mediterranean with the aim of protecting Turkish research ships namely Oruç Reis and Fatih (İşeri & Bartan, 2019). Another factor that has decreased mutual trust in Turkish-Greek relations have been Athens' refusal to extradite FETO suspects sheltering in Greece following the 2016 terrorist coup attempt. As the Economist (2017) put it, "Turkey and Greece are no longer at each other's throats"; however, "there is no room for improved relations". In this fragile security environment, Turkish foreign policy has moved from a cooperative, liberal approach to a re-securitized form.

CONCLUSION
The dramatic transformation in Turkish foreign policy back to its traditional realist and security-based mode in the 2010s was mainly the result of changes in the intensity of internal and external threats to Turkey. Arab Spring leading to the civil war in Syria made Turkey vulnerable to PKK as well as ISIS attacks. PKK terror, which can be considered as both an internal and external threat, has been a significant challenge to Turkey's territorial integrity. Turkish policy makers' initiative on the solution of separatist terrorism, has been misused by the PKK to re-initiate its attacks. In fact, the PKK never gave up violence even during the "democratic opening process" since it continued planting landmines all over towns in south-eastern Turkey. The obstruction of the process also coincided with the Syrian government's authorization of Kurdish autonomous administrations near the Turkish border. The control of these areas by YPG/PYD, the PKK's ally in Northern Syria, has led to a rise in PKK terror attacks against both civilians and Turkey's security forces causing death and injury of thousands during the recent period. In addition to PKK terror, ISIS attacks in major cities and south-eastern cities have also caused hundreds of casualties and forced the Turkish government to abandon its cooperative and liberal foreign policy. The immigration of more than 3,5 million Syrian citizens to Turkish cities has made it easier for PKK and ISIS terrorists to infiltrate Turkey's borders.
By the 2010s, the changing nature of Turkey's security environment and challenges to national security had a major impact on national foreign policy. Although the EU's decreasing influence on Turkish foreign policy had some minor effect on the re-securitization of Turkish foreign policy, this dramatic turn was mainly driven by the insecure environment resulting from the war in Syria, which increased the threats to Turkey from the PKK and ISIS, as well as the support they received from Turkey's neighbours. This has forced the Turkish government to start a national struggle against multiple terror organizations, with the implementation of cross-border military operations.