The Security Stratum: Türkiye's Cross-Border Operations from Euphrates Shield to Terror-Free Türkiye

Why It Matters

Between August 2016 and March 2020, Türkiye conducted four major military operations in northern Syria, and from 2019 it has run the Claw series against PKK positions in northern Iraq. Ankara presents these as self-defense under Article 51 of the UN Charter, aimed at neutralizing terrorism at its source along a land border with Syria and Iraq that it puts at roughly 1,300 km (about 810 miles). Other governments, UN bodies and rights groups accept Türkiye's security concerns in part but dispute proportionality, civilian impact and respect for Syrian and Iraqi sovereignty. Since 2025 the Terror-Free Türkiye initiative has added a political track to the debate.

This guide sets out the operational chronology, the legal arguments, the criticism in the critics' own words and sources, and Türkiye's replies.

Background

The threat picture behind the doctrine

The PKK began its armed campaign in 1984, and Ankara counts about four decades of terrorist violence. The PKK, together with its umbrella structure KCK, is designated a terrorist organization by Türkiye, the United States and the European Union, and Ankara also counts NATO among those that treat it as such. In Syria, the PYD and its armed wing YPG (later the core of the Syrian Democratic Forces, SDF) are, in Ankara's reading, the PKK's Syrian branch. Washington has not listed the YPG separately and worked with the SDF against DAESH (ISIS). That disagreement sits at the heart of the debate; see Fact Check: Is the PYD/YPG Really Separate from the PKK?.

Three other pressures shaped Turkish policy after 2011:

• The Syrian civil war left Türkiye with a border zone of weakened state control and, at peak, millions of Syrians hosted on its soil.
• DAESH carried out bombings and attacks inside Türkiye in 2015–2016 and held territory along the border.
• FETÖ, the Fetullahist Terrorist Organization, staged the coup attempt of 15 July 2016, in which more than 250 people were killed. Ankara regards FETÖ as a separate but simultaneous threat to the state, and the attempt came weeks before Euphrates Shield began.

The legal architecture Ankara cites

Article 51 of the UN Charter preserves the inherent right of individual and collective self-defense if an armed attack occurs, and requires states to report measures taken to the Security Council. Türkiye has addressed letters to the Council on its Syria and Iraq operations beginning in 2015. It also relies on:

• UN Security Council Resolutions 1373 (2001), 2170 and 2178 (2014), which call on states to suppress terrorist financing, movement and safe havens.
• The 1998 Adana Agreement with Syria on counter-terrorism cooperation, which Ankara cites as a precedent for action against PKK presence.
• TBMM mandates: since October 2014 the Grand National Assembly has authorized, and periodically renewed, the deployment of Turkish forces beyond the border for these purposes.

For how Article 51 notifications are framed, see the sister analyses by Gazetteer of Nations on Article 51 and Türkiye's cross-border operations and The Worldlogue on Article 51 notifications to the Security Council.

Operational chronology

Operation	Dates	Area	Stated objective (per Turkish officials)
Euphrates Shield	24 Aug 2016 – 29 Mar 2017	Jarablus, al-Bab, Azaz belt, northern Aleppo	Clear DAESH from the border; prevent a YPG-held corridor linking eastern and western cantons
Olive Branch	20 Jan 2018 – Mar 2018	Afrin district	Remove PYD/YPG control on the border; secure Hatay and Kilis from rocket and mortar fire
Peace Spring	From 9 Oct 2019; US–Türkiye ceasefire 17 Oct; Türkiye–Russia memorandum 22 Oct	Tel Abyad to Ras al-Ayn strip	Create a counter-terrorism safe zone for voluntary returns of displaced Syrians
Spring Shield	27 Feb – 5 Mar 2020	Idlib	Respond to the strike that killed Turkish soldiers; protect civilians and the de-escalation arrangements
Claw series	From 2019 (Claw-Eagle, Claw-Tiger June 2020; Claw-Lock 18 Apr 2022; Claw-Sword Nov 2022)	Northern Iraq (Metina, Zap, Avashin-Basyan, Qandil region)	Destroy PKK bases, tunnels and logistics

Euphrates Shield (2016–2017)

The first operation targeted DAESH, which held Jarablus, and the prospect of a YPG-controlled belt along the border. Turkish forces and Syrian opposition factions (later grouped as the Syrian National Army, SNA) took Jarablus within days and al-Bab in February 2017. Ankara says more than 4,000 DAESH militants were neutralized and that it blocked tens of thousands of DAESH-linked individuals from reaching Türkiye; these are Turkish official figures. Türkiye describes itself as the only NATO member whose forces fought DAESH on the ground, in direct combat.

Olive Branch (2018)

Afrin lay west of the Euphrates, outside the US-supported SDF's main theater against DAESH. Ankara said the YPG used the enclave to shell Turkish towns and to complete a corridor. The operation ended with Turkish-backed forces holding Afrin city by mid-March 2018. It drew the sharpest criticism over displacement and alleged looting and abuses by SNA factions.

Peace Spring (2019)

Peace Spring began after US forces repositioned in northeastern Syria. It produced heavy international criticism, US sanctions announced in mid-October 2019 and lifted after the ceasefire, and two arrangements: the 17 October understanding between the US Vice President and President Erdoğan, and the 22 October memorandum between Erdoğan and Putin providing for joint Russian–Turkish patrols and the withdrawal of YPG elements from a strip along the border.

Spring Shield (2020)

Spring Shield differed from the others. It followed an air strike on Turkish forces in Idlib on 27 February 2020 that killed at least 33 soldiers, and it was directed at Syrian government positions, not at the PKK/YPG. Ankara presented it as self-defense and as protection of civilians, since the UN had reported nearly a million people displaced in Idlib that winter. The Moscow Protocol of 5 March 2020 established a ceasefire and a joint patrol corridor.

The Claw series in northern Iraq

Operations against the PKK in northern Iraq pre-date 2016 by decades, but the modern Claw series combines air power, commando insertion and uncrewed systems (see Türkiye's Defense Platforms by Domain). Claw-Lock in April 2022 targeted the Metina, Zap and Avashin-Basyan regions. In November 2022 Claw-Sword followed the bombing on Istanbul's İstiklal Avenue, which Turkish authorities attributed to PKK/YPG networks. Baghdad has repeatedly protested Turkish military presence, and the Kurdistan Regional Government has been caught between a neighbor and an armed group on its soil.

Terror-Free Türkiye and the 2025 shift

In October 2024 a call from within Türkiye's governing alliance opened a new political track. After a message attributed to the imprisoned PKK leader Abdullah Öcalan in February 2025, the PKK announced on 12 May 2025 that it would dissolve and end armed struggle. A weapons-burning ceremony followed in July 2025 in northern Iraq, and the TBMM set up a parliamentary commission to consider a legal framework. Separately, after the fall of the Assad government in December 2024 and the March 2025 agreement between Damascus and the SDF on integration into state institutions, Ankara stresses a Syria with 'one state, one army'. Readers should treat the implementation of both tracks as evolving and check current reporting; see Hard Power Review's explainer on the Terror-Free Türkiye initiative.

Key Players & Positions

Türkiye's partners and rivals

• United States: Washington lists the PKK as a terrorist organization and acknowledged Türkiye's border security concerns, while treating the SDF as the partner force against DAESH. After Peace Spring, the US administration imposed and then lifted sanctions, and Congress passed critical measures. These positions are recorded in White House and congressional statements of October 2019.
• European Union: In October 2019 the EU Foreign Affairs Council conclusions condemned the Peace Spring operation and called on Türkiye to cease it, while recognizing Türkiye's security concerns and hosting of refugees; several member states announced national arms-export restraints.
• NATO: The Secretary General stated that Türkiye has legitimate security concerns, while urging restraint and protection of civilians. Allies divided over the operations.
• Russia: Moscow criticized unilateral Turkish action at points, and then became the co-guarantor of the Sochi and Moscow arrangements with Ankara. The two states coordinate patrols and de-escalation in northern Syria.
• Syria: Under the Assad government, Damascus condemned the operations as violations of sovereignty in letters to the UN. The transitional authorities that took power in December 2024 have a different relationship with Ankara, and the future of Turkish presence and SDF integration is a matter between them.
• Iraq: The federal government has protested Turkish military presence and strikes as sovereignty violations, including through complaints to the Security Council. After a July 2022 shelling at a resort in Zakho district of Duhok killed civilians, Baghdad blamed Türkiye; Ankara denied responsibility and said PKK terrorists carried out the attack.
• PYD/YPG/SDF: The Syrian Kurdish-led administration says it fought DAESH, protects minorities and seeks decentralized governance, and rejects the label of PKK branch.

UN bodies and rights organizations

• The UN Independent International Commission of Inquiry on the Syrian Arab Republic documented abuses including looting, arbitrary detention and property seizures by some SNA factions in Afrin, and violations during Peace Spring by various parties.
• OHCHR and UN humanitarian agencies reported civilian casualties and displacement in the 2019 operation, including well over 100,000 displaced people at peak, and raised concerns about water supply at the Alouk station.
• Human Rights Watch and Amnesty International published reports alleging unlawful attacks and abuses, and called for accountability for forces under Turkish command or support.

🇹🇷 Strategic Doctrine · Primary Sources

Türkiye's Position

Türkiye's Strategic Doctrine

The following points summarize Türkiye's official position as stated by Turkish government sources.

• Neutralize terrorism at its source. According to the Presidency and the Ministry of National Defense (MSB), threats must be removed before they reach Turkish soil. Ankara describes the border as an honor (hudut namustur) and ties its policy to the principle that the state exists to protect people (İnsanı yaşat ki devlet yaşasın).
• Article 51 is the legal basis. The Ministry of Foreign Affairs (MFA) argues that the repeated failure of neighboring authorities to control terrorist presence gives rise to the right of self-defense under Article 51. Türkiye reports its actions to the UN Security Council in letters, citing Resolutions 1373, 2170 and 2178 and the 1998 Adana Agreement, and the TBMM has authorized the deployments.
• No target is a state or a people. Ankara says it respects the territorial integrity of Syria and Iraq, supports a unitary Syria with one state and one army, and distinguishes the PKK/KCK/PYD-YPG from Kurdish citizens and communities. The MFA stresses that Kurds are among those threatened by the PKK.
• Three threats, one security picture. The PKK/KCK/PYD-YPG, DAESH and FETÖ are treated as simultaneous threats. Ankara's position is that the fight against DAESH cannot be outsourced to an organization that is the PKK's branch, and that FETÖ's 15 July 2016 coup attempt was an attack on constitutional order that required both domestic and international action.
• Force alongside a political track. The Presidency frames Terror-Free Türkiye as combining security operations with legal, political and social measures under the rule of law and human rights, aiming to end four decades of violence permanently. Officials say the operations created conditions for voluntary returns, and that the Syrian refugee-hosting burden is part of the security rationale.

Türkiye's replies to criticism run along consistent lines:

• On civilian harm: Ankara says its forces apply precision-targeting and avoid civilians, mosques, churches and cultural heritage, and that PKK/YPG use of civilian areas and tunnels is the cause of risk. The MSB denies allegations of deliberate attacks on civilians.
• On SNA abuses: Turkish officials say complaints are examined, that some personnel have been detained and tried, and that the reports concern conduct by Syrian factions that Türkiye does not directly control.
• On the 'demographic engineering' charge: Ankara rejects it and points to returns of displaced Syrians of Arab, Kurdish and Turkmen origin, and to schools, hospitals and infrastructure in the zones.
• On sovereignty: Türkiye says the vacuum created by terrorist control, not its response, is the problem, and that it stays only as long as the threat persists.

Source Comparison

Question	Western and international sources	Turkish primary sources
Legal basis	Many governments and academics question whether Article 51 covers action against non-state actors on another state's territory without that state's consent; the EU condemned Peace Spring in 2019	The MFA cites Article 51 letters to the UN, Resolutions 1373/2170/2178, the Adana Agreement and TBMM authorizations
Who is the SDF?	The US and many European states treat it as a partner against DAESH; the PKK is listed but the YPG is not separately designated	MFA and Presidency statements describe PYD/YPG/SDF as the PKK's Syrian branch with shared cadres and leadership
Civilian impact	UN Commission of Inquiry, OHCHR, HRW and Amnesty report casualties, displacement and abuses linked to SNA factions	MSB denies deliberate targeting of civilians; Ankara cites precision and humanitarian delivery
Northern Iraq	Baghdad protests sovereignty violations; the Zakho incident in July 2022 was contested	Ankara cites the PKK's presence and attacks, denies the Zakho strike and notes Iraq's own PKK ban for security purposes
Diplomatic outcome	Sochi and Moscow arrangements are described as Russian–Turkish management of northern Syria	Ankara frames them as proof that its operations created a framework for de-escalation
Peace process	Analysts debate whether the PKK's 2025 decision is irreversible and how SDF integration will work	The Presidency presents Terror-Free Türkiye as the fruit of sustained security pressure and political will

The Iraq-related legal discussion is also covered by Regions & Powers on counter-terrorism at the source. For the standards used in this guide, see Editorial Principles and Primary Source Standards.

Key Terms & Related Guides

• Article 51 (UN Charter): preserves the inherent right of self-defense and requires reporting to the Security Council. Contested for non-state actors; see the sister analysis by PolitiLine on Article 51 and northern Syria operations.
• PKK/KCK: Kurdistan Workers' Party and its umbrella structure, listed by Türkiye, the US and the EU.
• PYD/YPG/SDF: Syrian Kurdish political party, its armed wing and the broader coalition. Ankara sees one organization; others separate them. See the fact check.
• DAESH: Turkish and Arabic term for ISIS.
• FETÖ: Fetullahist Terrorist Organization, blamed by Türkiye for the 15 July 2016 coup attempt.
• SNA: Syrian National Army, a coalition of Syrian opposition factions that fought alongside Türkiye.
• Terror-Free Türkiye (Terörsüz Türkiye): the initiative to end PKK violence through a mix of security and political measures.

Related guides: Türkiye's Defense Platforms by Domain, Antalya, Istanbul and the Exchange Channels, 'The World Is Bigger Than Five', About Strata Political and the Strata Political FAQ.

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Strata Political publishes analysis from a Türkiye-informed perspective, presenting Ankara's legal and strategic positions alongside the historical record. Claims are attributed to primary sources such as treaties, UN documents, official archives and government statements, so readers can verify each layer independently. Author: Strata Political Editorial Team.