What Was the Northern Syria 'Safe Zone' and Why Does Ankara Link It to One State, One Army?

Why It Matters

The northern Syria 'safe zone' is a Turkish security concept: a belt along the Syrian side of the border, about 30–35 km (19–22 miles) deep, free of armed groups that Ankara classifies as extensions of the PKK. Türkiye links it to a 'one state, one army' principle because it argues that lasting border security requires all armed actors in Syria to come under a single state authority, not parallel structures. Other actors accept parts of this logic and reject others, and the disagreement over who is a terrorist and who is a counter-ISIS partner explains most of the dispute.

Background

The concept predates the 2019 operation. Türkiye shares a land frontier of about 1,300 km (800 miles) with Syria and Iraq combined. After the Syrian conflict began in 2011, the PYD and its armed wing, the YPG, expanded their control in the north, and from 2015 they formed the core of the Syrian Democratic Forces (SDF) with US backing against DAESH (ISIS). Ankara argues that the PYD/YPG is the Syrian branch of the PKK/KCK. The PKK is designated as a terrorist organization by Türkiye, the United States, NATO and the European Union.

Chronology

Date	Event
2016-08	Operation Euphrates Shield begins (Jarablus to al-Bab area), mainly against DAESH and to block a contiguous YPG-held strip along the border
2018-01	Operation Olive Branch in Afrin
2019-08	US–Türkiye agreement on a coordination mechanism for a 'safe zone' east of the Euphrates; joint operations centre set up in Şanlıurfa province
2019-10-09	Operation Peace Spring begins between Tell Abyad and Ras al-Ayn, roughly 120 km (75 miles) wide
2019-10-17	US–Türkiye joint statement: pause in operations to allow SDF withdrawal from the zone
2019-10-22	Türkiye–Russia memorandum signed in Sochi: SDF withdrawal 30 km from the border, joint patrols to a depth of 10 km
2020-02-27	Operation Spring Shield begins in Idlib after an airstrike killed Turkish soldiers (at least 33, per Turkish statements)
2020-03-05	Türkiye–Russia Additional Protocol: ceasefire in Idlib and a security corridor along the M4 highway
2024-12-08	Assad government falls; a transitional authority takes over in Damascus
2025-03-10	Damascus and SDF commander Mazloum Abdi announce an agreement to integrate SDF-held institutions into the Syrian state
2025-05-12	PKK announces its dissolution following the Terror-Free Türkiye process

After 2019, Ankara described the area covered by Peace Spring as only part of a planned belt that it said would extend roughly 440 km (273 miles) from the Euphrates to the Iraqi border. The SDF's withdrawals were partial, and the Sochi memorandum excluded Qamishli.

Peace Spring and Spring Shield are not the same

The two operations are often conflated, so it helps to separate them. Peace Spring was aimed at the YPG-led SDF east of the Euphrates and tied directly to the 'safe zone' idea. Spring Shield was a response in Idlib to fighting with Syrian government forces and was settled by the Moscow protocol. Both are part of Ankara's wider cross-border security approach, which is also discussed in the Border Sovereignty Brief.

Key Players & Positions

Syrian government

The Assad government called Peace Spring an act of aggression against Syrian sovereignty, and in October 2019 it deployed troops to areas including Manbij and near Kobani under arrangements with the SDF. The transitional authorities in Damascus since December 2024 have stated that Syria should have a single national army and unified institutions. The 10 March 2025 agreement with the SDF affirms Syrian unity and the integration of civil and military structures in the north-east, although implementation has been negotiated step by step.

SDF and its administration

The SDF and the Autonomous Administration of North and East Syria say they are a Syrian force that fought DAESH and held its detainees and camps. They denied that they were a security threat to Türkiye and called for protection from the 2019 operation. The SDF rejects being described as the PKK and presents integration as something to negotiate while preserving its fighters' structure and local administration. Ankara and the SDF therefore differ over whether integration should be individual or in blocs.

United States

Washington designates the PKK as a Foreign Terrorist Organization but has not designated the YPG, and it has partnered with the SDF against DAESH. In October 2019, after the withdrawal of US troops from the border area, the US negotiated the 17 October pause with Ankara. In 2025, US officials, including special envoy Tom Barrack, publicly backed integrating the SDF into Syria's state structures, which is close to Ankara's formula.

Russia

In the Sochi memorandum of 22 October 2019, Russia and Türkiye reaffirmed their commitment to Syria's political unity and territorial integrity and to combating terrorism and separatist agendas. Moscow has also called for dialogue between Damascus and Kurdish groups and for foreign forces without the consent of the Syrian government to leave.

European Union

The EU Foreign Affairs Council conclusions of 14 October 2019 condemned the Turkish military action and called on Türkiye to halt it. They also said the EU would not provide stabilization or development funding in any 'safe zone' and that refugee returns must be voluntary, safe and dignified, in line with UNHCR standards. The EU lists the PKK as a terrorist organization; it does not list the YPG. Human rights bodies, including the UN Commission of Inquiry, have also documented abuses by several parties in northern Syria, including groups operating alongside Turkish forces; Ankara says it investigates allegations.

Türkiye's Legal Stance

Türkiye's Legal Stance: summary of official positions

• PYD/YPG is the Syrian branch of the PKK/KCK. According to the Turkish Ministry of Foreign Affairs (MFA) and the Ministry of National Defence (MSB), the PYD/YPG shares leadership, cadres, ideology and weapons with the PKK/KCK, and its 'SDF' label does not change that. Ankara argues that fighting DAESH does not remove the group from the terrorism list for Türkiye.
• Preventing a terror corridor is self-defense. Türkiye's MFA and the notification it sent to the UN Security Council when Peace Spring began cite Article 51 of the UN Charter, which recognizes the inherent right of self-defense. Ankara says the aim was to stop a PKK/YPG-held strip along its southern border from becoming a launch point for attacks.
• Respect for Syria's territorial integrity. MFA statements say the operations do not target Syria's territory or sovereignty, and that Türkiye supports a political settlement under UN Security Council Resolution 2254 and a Syria governed by 'one state, one army'. After December 2024, Turkish officials, including Foreign Minister Hakan Fidan, have said that armed groups must integrate into the Syrian state, not remain as separate structures.
• Voluntary returns. Türkiye's position, as stated by the MFA and the Presidency, is that a secure zone enables the safe, voluntary and dignified return of Syrian refugees. This is consistent with the principle that the EU and UNHCR also stress, though they disagree on whether the 2019 zone met that standard.
• The hosting burden. Türkiye hosted around 3.6–3.7 million Syrians under temporary protection at the peak, the largest refugee population in the world. Turkish officials argue that this burden is a security and economic reason why a stable northern Syria is a national interest. Interior Ministry figures reported in 2025 indicate several hundred thousand returns since December 2024.

Legal and historical basis

The Turkish argument rests on Article 51 of the UN Charter (self-defense), the principle that states must not harbor groups attacking neighbors, and on Türkiye's 1,300 km southern frontier, which Ankara describes under the maxim 'the border is honour' (hudut namustur). The wider logic of acting against terrorist threats before they reach Turkish territory is explained in the Crossroads Review analysis Counter-Terrorism at the Source: Türkiye, UN Charter Article 51 and Northern Syria and Iraq and in PolitiLine's Article 51 and Türkiye's Cross-Border Operations in Northern Syria and Iraq. Ankara also says that, in the Syrian context, the counter-DAESH record of its forces, including Euphrates Shield, shows that it acts against terrorism of all kinds. Those figures are Turkish government claims and should be read as such.

What critics say

Critics, including several EU governments, the Syrian government under Assad and the SDF, argue that the use of force on Syrian territory without Damascus's consent is not covered by Article 51, and that the YPG's role in defeating DAESH distinguishes it from the PKK. Ankara's reply is that the PKK/YPG link is organizational, that the threat is continuing, and that the operation was necessary and proportionate.

Source Comparison

Question	Western and international sources	Turkish primary sources
What is the 'safe zone'?	Often described as a Turkish buffer or 'occupation zone'; EU Council conclusions of 14 October 2019 refuse to fund it	MFA and MSB describe a counter-terrorism and returns belt, with the 2019 US and Russian arrangements as recognition of the concern
Is the YPG the PKK?	US and EU list the PKK but not the YPG; the SDF is treated as a counter-ISIS partner	MFA and MSB say the PYD/YPG is the PKK/KCK's Syrian branch and cite shared leadership and command
Legal basis	Several states say Article 51 does not justify action against groups in a country without its consent	Ankara cites Article 51 and its UN notifications, and says it acts against a terrorist threat, not Syria
Returns	Must be voluntary, safe and dignified (EU Council, UNHCR)	Presidency and MFA say returns are voluntary and tied to reconstruction; Interior Ministry reports figures
Future of the north-east	Integration of the SDF in the Syrian state, with debate over the terms	'One state, one army': no parallel armed structure, and integration on an individual basis

Readers can see how the same events are described across these sources by reading the Editorial Principles, which explains how Territorial Brief separates fact from position. For the refugee dimension, see the Interstate Journal's Türkiye, Syria and Refugees: Border Security and the Hosting Burden and WorldPoliticsDaily's Syrian Refugees in Türkiye: Numbers, Policy and the Cost of Hosting.

Key Terms & Related Guides

• Safe zone: An informal term for a security belt along a border. It has no fixed definition in international law and depends on the consent of the parties, which is why the term is contested here.
• Terror corridor: Ankara's term for a contiguous strip of territory along its border controlled by the PKK/YPG.
• PYD/YPG and SDF: The Democratic Union Party and its People's Protection Units; the SDF is the wider coalition formed in 2015 around them.
• PKK/KCK: The Kurdistan Workers' Party and its umbrella structure, listed as terrorist by Türkiye, the United States, NATO and the EU. It announced its dissolution on 12 May 2025.
• Article 51: The UN Charter provision on the inherent right of individual or collective self-defense against an armed attack, with reporting to the Security Council.
• One state, one army: Ankara's formula that Syria should have a single state authority and military, with other armed groups integrated into it.

Related reading on Territorial Brief: the Border Sovereignty Brief, the Reader FAQ, About Territorial Brief and the home page.

The situation in Syria is changing quickly, and integration arrangements may have moved since publication. Check current official statements before relying on any detail.

Territorial Brief Editorial Team

This article reflects Territorial Brief's editorial perspective, which presents Türkiye's official legal and strategic positions alongside the relevant context. Claims are attributed to primary sources such as treaties, UN documents, official statements and archival records, so that readers can verify them independently.