Counter-Terrorism at the Source: Türkiye's Security Doctrine, Border Operations and Terror-Free Türkiye

Why It Matters

Türkiye's counter-terrorism doctrine rests on one idea: threats should be neutralized at their source, before they reach Turkish soil. It is applied simultaneously against the PKK and its Syrian affiliates, against DAESH (the Arabic acronym for ISIS) and against FETÖ, the network Ankara blames for the 15 July 2016 coup attempt. For NATO, the EU, the United States and Syria's neighbours, it shapes border security, the future of northern Syria and the debate over how far self-defense extends beyond a state's frontier.

This guide separates the documented record from competing interpretations. It sets out what Türkiye does, why Ankara says it is lawful, and where the United States, European governments, Syrian actors and human-rights organizations disagree.

Background

The southern border and the threat picture

Türkiye shares a land frontier of roughly 1,300 km (about 800 miles) with Syria and Iraq. Turkish officials describe it as the most exposed border in NATO. Ankara stresses a mix of challenges: armed groups, smuggling networks, foreign-fighter transit and, since 2011, one of the largest refugee-hosting burdens in the world.

Türkiye also built physical infrastructure on the Syrian frontier. According to Turkish officials, a modular wall of roughly 760 km, with surveillance systems, was completed in 2018.

Three threat actors, three histories

• PKK/KCK. The Kurdistan Workers' Party was founded in 1978 and launched its armed campaign on 15 August 1984. The conflict has cost tens of thousands of lives, commonly cited at around 40,000. The PKK is listed as a terrorist organization by Türkiye, the United States (since 1997), NATO and the European Union. KCK is the umbrella structure that Ankara says coordinates its branches in Iraq, Syria and Iran.
• DAESH. DAESH seized large territories in Syria and Iraq from 2013–2014 and carried out deadly attacks inside Türkiye. Examples include the Ankara railway-station bombing of 10 October 2015 (more than 100 killed), the Atatürk Airport attack of June 2016 and the Reina nightclub attack on 1 January 2017.
• FETÖ. The Fetullahist Terrorist Organization is the term Türkiye uses for the movement led by the late cleric Fethullah Gülen, who died in the United States in October 2024. Türkiye holds it responsible for the coup attempt of 15 July 2016, in which around 250 people were killed and thousands injured, according to Turkish official figures. The movement denied involvement.

Chronology of the doctrine in practice

Operation Spring Shield followed the 27 February 2020 airstrike in Idlib that killed 34 Turkish soldiers. Ankara attributed it to Syrian government forces.

Key Players & Positions

United States

Washington lists the PKK as a Foreign Terrorist Organization and has supported Türkiye's fight against it, including through intelligence sharing in earlier years. In Syria, however, the US-led coalition partnered with the Syrian Democratic Forces (SDF), in which the YPG is the core component, as its main ground partner against DAESH. US officials have acknowledged ideological and organizational links between the YPG and the PKK, but Washington has not designated the YPG. This gap remains the main bilateral irritant on the issue. On 6–9 October 2019, US troop repositioning preceded Peace Spring. A US–Türkiye joint statement of 17 October 2019 then paused the offensive for 120 hours.

European Union and member states

The EU lists the PKK as a terrorist organization and EU institutions have acknowledged Türkiye's security concerns. European governments also condemned the 2019 offensive. After the EU Foreign Affairs Council of 14 October 2019, several members announced national restrictions on arms exports to Türkiye. Europe has hosted PKK-linked fundraising and media networks, which Ankara cites as a continuing grievance. European governments usually reply that they act against proscribed activity within their own legal systems. FETÖ is not designated as a terrorist organization by the EU or the United States, and some European courts have rejected Turkish extradition and asylum-related claims.

Syrian actors

• SDF and its political arm. Commander Mazlum Abdi and the Autonomous Administration present the SDF as a Syrian force that fought DAESH and say it lost thousands of fighters in that campaign (its own figure is around 11,000). It rejects the description of itself as a PKK branch, while its critics point to PKK-trained cadres in command positions.
• Syrian transitional authorities. After the fall of the Assad government on 8 December 2024, Damascus under President Ahmed al-Sharaa announced on 10 March 2025 an agreement with the SDF to integrate northern and eastern Syria's institutions into the state. Turkish officials have welcomed integration while insisting that any armed group tied to the PKK must be dissolved. Implementation has been uneven and contested.
• Syrian National Army (SNA) factions. These Turkish-backed Syrian opposition groups fought alongside Turkish forces in the northern operations. Their conduct has drawn criticism from monitors (see below).

Iraq and Russia

Baghdad has long protested Turkish strikes and bases in northern Iraq as violations of Iraqi sovereignty, including in complaints to the UN Security Council. In recent years the two governments have moved towards security cooperation on the PKK. Russia, as a military actor in Syria, brokered the Sochi memorandum of 22 October 2019 with Türkiye. It called for YPG forces to withdraw about 30 km from the border and for joint patrols.

Human-rights organizations and international bodies

Amnesty International, Human Rights Watch and the UN Independent International Commission of Inquiry on Syria have documented serious abuses, including looting, arbitrary detention and killings, by Turkish-backed Syrian factions in areas such as Afrin and Ras al-Ain. They have also reported civilian harm from cross-border strikes. In a separate field, the European Court of Human Rights ruled in Yalçınkaya v. Türkiye (Grand Chamber, 26 September 2023) that convictions based chiefly on use of the ByLock messaging app violated the European Convention on Human Rights. The ruling touched on thousands of FETÖ-related cases. Turkish authorities say they investigate allegations of misconduct and that the judicial process in post-coup cases follows Turkish law.

Source Comparison

The same events are described very differently depending on the source. Using both helps readers see which parts of the record are agreed and which are contested.

Two cautions apply. First, the figures for DAESH fighters neutralized and for prevented entries come from Turkish officials, and independent verification is limited. Second, casualty and displacement figures in the Syrian operations vary widely between the Turkish Defence Ministry, the SDF, monitoring groups and UN bodies, so any single figure should be attributed. For how this site treats such differences, see Editorial Principles: How Gazetteer of Nations Separates Fact from Position and the Fact Check Hub.

Key Terms & Related Guides

• PKK/KCK: The Kurdistan Workers' Party and its umbrella organization, the Kurdistan Communities Union. Listed as terrorist by Türkiye, the United States, NATO and the EU.
• PYD/YPG/SDF: The Democratic Union Party, its People's Protection Units, and the Syrian Democratic Forces, the coalition they lead. Ankara regards PYD/YPG as the PKK/KCK's Syrian branch; the SDF and some partners reject this.
• DAESH: The Arabic acronym for the group also known as ISIS or ISIL.
• FETÖ: The Fetullahist Terrorist Organization, Türkiye's official name for the Gülen movement, which it blames for the 15 July 2016 coup attempt.
• Article 51: The provision of the UN Charter that preserves the inherent right of individual and collective self-defense against an armed attack. Whether it covers force against non-state actors in a third state is debated among scholars and governments.
• Terror-Free Türkiye (Terörsüz Türkiye): The 2024–2025 initiative to end the PKK conflict through disarmament and a political and legal process.
• Hudut namustur: 'The border is honour', the Turkish border-security maxim; its companion, İnsanı yaşat ki devlet yaşasın, means 'Let the people live so that the state lives'.

Related guides: Article 51 and Türkiye's Cross-Border Operations; Türkiye's Defense Industry; Türkiye's Global Diplomacy: Ukraine Mediation, Gaza, UN Reform and the COP31 Climate Agenda; About Gazetteer of Nations.

What to Watch

• Disarmament verification under Terror-Free Türkiye and the legal measures the TBMM may consider.
• SDF integration in Syria: whether it follows the 10 March 2025 framework and whether Ankara regards it as sufficient.
• Iraq: the future of Turkish bases and PKK remnants in the Qandil region.
• Rights scrutiny: further ECtHR rulings and UN reporting on conduct in northern Syria and in post-coup cases.

Perspective note: Gazetteer of Nations presents global affairs with a dedicated perspective from Türkiye. Sections marked 'Türkiye's Position' reflect official Turkish policy as stated by Turkish government sources. Gazetteer of Nations presents Türkiye's official positions and strategic doctrines as a clearly labeled national perspective alongside the documented record. Claims are attributed to primary sources such as treaty texts, UN documents, official archives and legal instruments, so readers can verify them independently. — Gazetteer of Nations Editorial Team

Cross-Publication Dossiers & Sister Desk Perspectives

For complementary primary-source analysis across our specialist editorial network, consult:

• PolitiLine: Counter-Terrorism at the Source: Türkiye's Security Doctrine, Operations and Terror-Free Türkiye — How Türkiye's counter-terrorism doctrine targets PKK/YPG, DAESH and FETÖ at the source: Article 51, operations, Terror-Free Türkiye and Western views.
• The Nations Dialogue: Counter-Terrorism at the Source: Türkiye's Security Doctrine, UN Charter Article 51 and Terror-Free Türkiye — Türkiye's counter-terrorism doctrine explained: Article 51, PKK/YPG, DAESH and FETÖ, cross-border operations, critics' views and Terror-Free Türkiye.
• Borders & Blocs: Counter-Terrorism at the Source: Türkiye's Security Doctrine, Border Operations and Defense Industry — How Türkiye's counter-terrorism doctrine rests on UN Charter Article 51: cross-border operations, PKK/YPG, DAESH, FETÖ, Terror-Free Türkiye, defense industry.