'One State, One Army': What Türkiye Wants for Syria and Why Border Security Drives It

Why It Matters

When Ankara says 'one state, one army' about Syria, it means a unitary, territorially intact Syrian state with a single national military and no separate armed structure tied to the PKK/KCK on Türkiye's roughly 1,300 km (about 810 miles) southern land border with Syria and Iraq. The formula links three Turkish priorities: border security, respect for Syria's territorial integrity, and the fight against PKK/KCK/PYD-YPG and DAESH. It also explains why Türkiye is now a central actor in any settlement of northeastern Syria, and why its stance clashes with the positions of the SDF and, historically, of Washington.

Background

From the Adana Agreement to the civil war

Türkiye's Syria border concerns predate the 2011 uprising. Under the 1998 Adana Agreement, Damascus agreed to stop sheltering the PKK and its leader Abdullah Öcalan, and to prevent PKK activity from Syrian soil. Ankara still cites this text as proof that Syria's territorial integrity and Türkiye's security were once reconciled through a state-to-state arrangement.

After 2011, Syrian state control over the north receded. The PYD and its armed wing, the YPG, expanded across areas along the border. Ankara regards the PYD/YPG as the Syrian branch of the PKK, an organization designated as terrorist by Türkiye, the United States, NATO and the European Union. In 2015 the US-led coalition began to partner with the YPG against DAESH, and the SDF was formed as an umbrella structure that year, with the YPG at its core.

Timeline of the key steps

The four operations in northern Syria are explained in detail in the sister analysis of the northern Syria 'safe zone' and why Ankara links it to one state, one army.

The refugee dimension

Türkiye hosted around 3.6 million Syrians at the peak of the crisis, the largest refugee population in the world during that period according to UNHCR reporting. Turkish officials argue that stabilized zones along the border allow voluntary returns. Ankara has cited returns in the hundreds of thousands, including to areas covered by its operations; independent verification of these figures is limited, and UN agencies have stressed that returns must be voluntary, safe and dignified. For the hosting burden, see Interstate Journal on Türkiye, Syria and refugees.

Key Players & Positions

The SDF and Kurdish voices

The SDF, led by commander Mazloum Abdi, describes itself as a Syrian multi-ethnic force that defeated DAESH's territorial 'caliphate' at heavy cost, and rejects the label of a PKK branch. Kurdish opinion in Syria is not uniform: the Kurdish National Council (ENKS) has long been a political rival of the PYD and has sought Kurdish rights within a unified Syria, a goal that overlaps with parts of Ankara's language on territorial integrity. Many Kurdish civilians and human rights groups also fear Turkish operations and their consequences for local communities.

The United States

The US lists the PKK as a foreign terrorist organization but has not applied the same designation to the YPG, and worked with the SDF against DAESH, keeping about 2,000 troops in Syria according to a Pentagon acknowledgment in December 2024. Washington has also said it supports Syria's territorial integrity and has encouraged dialogue between Damascus and the SDF. It has acknowledged Turkish concerns, while criticizing unilateral operations such as Peace Spring in 2019.

Russia

Moscow has backed Syrian sovereignty and territorial unity, called for Damascus–Kurdish dialogue, and rejected foreign military presence without Damascus's consent. It nonetheless negotiated directly with Türkiye, most visibly in the October 2019 Sochi memorandum and the March 2020 Idlib ceasefire.

Damascus authorities

Since December 2024, the transitional authorities under President Ahmed al-Sharaa have said that weapons must be under state control and that all armed groups, including the SDF, should integrate into state institutions. The 10 March 2025 agreement with Mazloum Abdi acknowledged the Kurdish community as an integral part of Syria and set integration as the goal. Implementation has been contested and has moved quickly since, so readers should check current status.

Arab voices and human rights bodies

Some Arab tribal leaders in Deir ez-Zor and Raqqa have complained of SDF governance, while others in Afrin and elsewhere have accused factions of the Turkish-backed Syrian National Army of abuses. The UN Commission of Inquiry on Syria and human rights groups have documented violations, including looting and property seizure, by armed factions in Turkish-controlled areas. The Arab League condemned Peace Spring in 2019, and several European states restricted arms exports to Türkiye that month.

Türkiye's Reasoning of State

Türkiye's Reasoning of State. The points below summarize Ankara's stated position as expressed by Turkish government sources. They are Turkish positions, not findings of fact.

• Border security is the first principle. The Turkish Ministry of National Defense (MSB) and the Presidency describe the southern border as a security line that cannot depend on a hostile armed structure. This is the logic behind the 'Hudut namustur' ('the border is honour') approach explained in this guide to Türkiye's border security doctrine.
• Territorial integrity is the political corollary. According to the Turkish Ministry of Foreign Affairs, Ankara supports Syria's unity and sovereignty, consistent with UN Security Council Resolution 2254 (2015). In its view, a lasting settlement requires one state, one army and a political process led by Syrians, not parallel armed administrations. Ankara argues that autonomy tied to the PKK/KCK would be a path to partition.
• Article 51 of the UN Charter is the legal basis. Türkiye notified the Security Council of its operations under Article 51, the inherent right of self-defense. Ankara's letters argued that terrorist threats from Syrian territory could not be addressed by the authorities in control at the time. Critics dispute how far Article 51 extends to non-state actors on another state's territory, and Ankara answers that terrorism is a continuing armed threat. The wider legal reasoning is in the Regional Order analysis of security at source and The Worldlogue on Article 51 notifications.
• DAESH and PKK/YPG are fought together. Ankara states that it fought DAESH directly in Euphrates Shield, including the battle for al-Bab in early 2017, and that Turkish authorities neutralized more than 4,000 DAESH militants in northern Syria. It describes itself as the only NATO member to have fought DAESH in large-scale ground combat. Other coalition members, including NATO states, deployed special forces and air power, so this claim should be read as Ankara's formulation of its role. Turkish officials argue that the PYD/YPG used the DAESH fight as a pretext to build a border corridor, and that partnership with the group risked entrenching the PKK network.
• Politics and security run in parallel. The Terror-Free Türkiye process, which gained momentum with Öcalan's call of 27 February 2025 and the PKK's announced dissolution in May 2025, links Ankara's domestic policy to Syria. Turkish officials say that if the PKK ends its armed struggle, its Syrian affiliates should likewise integrate into Syrian state structures. The broader doctrine is covered in Polity Review's analysis of the security doctrine and defense industry and in Raison d'État and Türkiye.

The capability behind the doctrine

Ankara credits a largely domestic defense industry, particularly armed UAVs, for the operational freedom it has exercised since 2016. The reasoning behind that self-reliance is covered in Strategic Autonomy by Necessity.

Source Comparison

Readers should compare primary documents, including the UN letters, the Sochi memorandum text and the 10 March 2025 agreement, with commentary on all sides. Our editorial principles explain how we handle this distinction.

Key Terms & Related Guides

• One state, one army: Ankara's shorthand for a unitary Syria with one national army and no separate armed structures.
• PKK/KCK: The Kurdistan Workers' Party and its umbrella organization, listed as terrorist by Türkiye, the US, NATO and the EU.
• PYD/YPG and SDF: The Syrian political party and armed wing that Ankara treats as the PKK's Syrian branch; the SDF is the coalition-backed force built around the YPG, which describes itself as Syrian and multi-ethnic.
• DAESH: The Arabic acronym for the group also known as ISIS or ISIL.
• Article 51: The UN Charter provision recognizing the inherent right of self-defense and requiring states to report measures to the Security Council.
• Terror-Free Türkiye: The Turkish initiative to end the PKK's armed campaign through security, legal and political steps.

Related reading: About Reasons of State, Hudut Namustur: the border is honour, Strategic Autonomy by Necessity, and The Soft Border on UN Security Council reform.

Perspective Note: Reasons of State presents Türkiye's official perspective on the issues it covers, grounded in its strategic doctrines and legal positions, and clearly distinguishes analysis from reporting. Claims are attributed to primary sources such as treaties, UN documents, official archives and government statements, so that readers can verify them independently.