Türkiye's Southern Security Belt: Border Doctrine, Cross-Border Operations and the Defense Industry Behind Them

Why It Matters

Türkiye’s southern border is where a doctrine of “neutralizing terrorism at its source” meets international law, regional politics and a fast-growing defense industry. Ankara argues that the roughly 1,300 km (about 800 miles) frontier with Syria and Iraq can only be secured by acting beyond it, invoking the right of self-defence in Article 51 of the UN Charter. Washington, Brussels, Damascus and Kurdish political actors each read the same events differently, and this guide sets out the chronology, the competing positions and the evidence so readers can judge for themselves.

For a wider view of how security fits into the publication’s coverage, see The Strategic Corridor: Türkiye at the Crossroads of Energy, Trade, Security and Law.

Background

Geography and the threat picture

The land border with Syria is roughly 900 km and the border with Iraq roughly 370 km, which together give the figure of about 1,300 km. Turkish officials describe the frontier with the motto “Hudut namustur” (“The border is honour”). The terrain, which includes mountain ranges in the east and flat plains in the south, has long been used for smuggling and infiltration.

Three organizations dominate Ankara’s threat assessment:

• PKK/KCK: The Kurdistan Workers’ Party, founded in 1978, began an armed campaign in 1984. It is listed as a terrorist organization by Türkiye, the United States, NATO and the European Union. The KCK is its umbrella organization. The commonly cited toll of the conflict exceeds 40,000 lives.
• PYD/YPG: The Democratic Union Party and its People’s Protection Units in Syria. Türkiye regards them as the Syrian branch of the PKK/KCK. The YPG is the core of the Syrian Democratic Forces (SDF), which the US partnered with against DAESH. Neither the US nor the EU lists the YPG as a terrorist organization.
• DAESH (ISIS): The jihadist group that seized large areas of Syria and Iraq from 2014 and carried out deadly attacks in Türkiye, including the Suruç bombing (July 2015) and the Ankara bombing (October 2015, more than 100 killed).

A fourth strand is FETÖ, the Fetullahist Terrorist Organization. Türkiye holds it responsible for the 15 July 2016 coup attempt, in which more than 250 people were killed. FETÖ is a domestic and diplomatic file rather than a border one, but it shapes the security posture. Many Western governments have not adopted Ankara’s terrorist designation and have raised concerns about the scope of the post-2016 purges.

Legal backdrop

The 1998 Adana Agreement between Türkiye and Syria committed Damascus to stop supporting the PKK and to act against its presence in Syria. Ankara still cites it. Article 51 of the UN Charter preserves the “inherent right of individual or collective self-defence if an armed attack occurs” and requires measures taken to be reported immediately to the Security Council. Ankara has also referred to Security Council resolutions on terrorism, including 1373 (2001), 2170 and 2178 (2014). The legal debate over whether Article 51 covers action against non-state actors on another state’s territory is covered in Gazetteer of Nations: Article 51 of the UN Charter and Türkiye’s Cross-Border Operations in Syria and Iraq.

Chronology of cross-border operations

Dates	Operation	Area	Stated Turkish objective	Notable context
24 Aug 2016 – 29 Mar 2017	Euphrates Shield	Jarablus to al-Bab, northern Aleppo	Clear DAESH from the border and prevent the YPG-held cantons from linking up	Turkish forces fought DAESH directly, including at al-Bab (Feb 2017). Ankara cites roughly 2,000 km² cleared.
20 Jan – Mar 2018	Olive Branch	Afrin	Remove PYD/YPG forces on the border; Ankara cites attacks into Hatay and Kilis	Afrin city taken 18 Mar 2018. UN bodies and human-rights groups later reported abuses by some Syrian opposition factions and displacement of residents.
9 Oct 2019	Peace Spring	Tell Abyad to Ras al-Ayn	Create a “safe zone” and break the planned “terror corridor”	17 Oct US–Türkiye understanding; 22 Oct Sochi memorandum with Russia on joint patrols. Strong European and US congressional criticism.
27 Feb – 5 Mar 2020	Spring Shield	Idlib	Respond to an airstrike that killed 33 Turkish soldiers on 27 Feb	Aimed at Syrian government forces, not the PKK/YPG. Ended with the 5 Mar Moscow protocol ceasefire.
From 2019 (various phases)	Claw series (Claw, Claw-2, Claw-Eagle, Claw-Tiger, Claw-Lock, others)	Northern Iraq, with air strikes in Syria	Eliminate PKK bases, caves and supply routes	Claw-Lock began April 2022; air strikes in Iraq and Syria followed the November 2022 Istanbul bombing. Baghdad has objected to Turkish presence.

Two later developments changed the context. The Assad government fell on 8 December 2024, and Syria’s new authorities now govern from Damascus. In Türkiye, the “Terror-Free Türkiye” process began after calls in late 2024 and imprisoned PKK founder Abdullah Öcalan’s appeal of 27 February 2025. The PKK announced its dissolution on 12 May 2025 and held a symbolic weapons-destruction ceremony in northern Iraq in July 2025. Implementation is ongoing and verification remains debated, so readers should check current reporting.

The defense-industrial layer

The operations coincided with a major expansion of Turkish defense manufacturing. Turkish officials say domestic production rose from roughly 20% in the early 2000s to about 80% today. The reasons they give include the 2019 removal from the F-35 programme, restrictions on some Western components, and US CAATSA sanctions on the Presidency of Defense Industries (SSB) in December 2020 after the S-400 purchase.

The main platforms linked to the southern belt are:

• Uncrewed systems: Bayraktar TB2 (used in Idlib, Libya, Nagorno-Karabakh and Ukraine), Akıncı, Aksungur, ANKA, plus Kargu loitering munitions and Bayraktar Kızılelma, an uncrewed combat aircraft that first flew in December 2022.
• Air: Hürjet advanced jet trainer and light combat aircraft (first flight April 2023), the ATAK helicopter and KAAN, a fifth-generation fighter (first flight February 2024).
• Naval: TCG Anadolu, a multi-purpose amphibious assault ship commissioned in April 2023, and MİLGEM corvettes and frigates.
• Missiles and air defense: ATMACA, SOM, Cirit and UMTAS, and the HİSAR-O medium-altitude air-defense system, with SİPER for longer range in the planned “Steel Dome” layered architecture.
• Land and electronic warfare: Fırtına howitzers, Kirpi mine-protected vehicles and the MEMATT uncrewed demining vehicle, along with the VURAL, KORAL, MİLKAR and MİLKED radar and electronic warfare systems.

What the “80%” figure measures

The 80% figure is a programme-level domestic-share indicator published by Turkish defense authorities; public detail on the methodology is limited. It signals that Turkish firms hold design authority and produce most of the value in most projects. It does not mean every sub-system is made in Türkiye. Notable dependencies have included engines (early TB2s used an Austrian Rotax engine, Akıncı uses a Ukrainian-designed engine, and KAAN prototypes and Hürjet rely on US-made engines), and optical sensors (Canada suspended exports of such sensors in 2019–2020, which accelerated Turkish substitutes). TCG Anadolu is based on a Spanish design. Definitions of “indigenous” and “local content” also differ between countries, so cross-country comparisons are imprecise. Two sister-site explainers cover the debate: Regions & Powers on the 80% claim and Monitor of Nations on how it was reached.

Key Players & Positions

United States

Washington lists the PKK as a Foreign Terrorist Organization and has supported Türkiye’s stated right to defend itself against it. It has also partnered with the SDF as its principal ground partner against DAESH since 2014–2015, and it does not list the YPG. The US opposed the October 2019 offensive and negotiated a ceasefire on 17 October 2019. Turkish and US officials have repeatedly said the arrangement is a source of friction inside NATO. Washington’s approach has shifted since the fall of the Assad government and the March 2025 understanding between Damascus and SDF leadership on integrating the SDF into state institutions, and US officials have backed that integration.

European Union and member states

The EU lists the PKK as a terrorist organization and acknowledges Türkiye’s security concerns. EU institutions and several member states criticised Operation Peace Spring: the Council’s October 2019 conclusions urged an end to the offensive, and a number of member states, including Germany, France and the Netherlands, announced restrictions on arms exports to Türkiye. EU bodies have also raised international humanitarian law, displacement and the post-operation situation in areas under Turkish-backed control.

Syria

The Assad government called the operations violations of Syrian sovereignty and territorial integrity and demanded Turkish withdrawal, and Russia and Iran broadly supported that view while managing the situation through the Astana format. The post-December 2024 authorities have pursued closer coordination with Ankara, while stating that the state should hold a monopoly on weapons. This is close to Ankara’s own “one state, one army” formula. The extent of formal agreements and future Turkish military presence remains subject to negotiation.

Iraq and the Kurdistan Region

The federal government in Baghdad has repeatedly protested Turkish military presence and strikes as sovereignty violations. In 2024 it also moved to formally ban the PKK, and Ankara describes this and the Iraqi-Turkish security cooperation that followed as positive steps. Kurdistan Regional Government officials have expressed concern about civilian harm in border areas while also opposing PKK activity on their territory.

Kurdish parties

The PYD, the SDF and the Autonomous Administration of North and East Syria say they are a Syrian force that bore the main ground burden against DAESH, with SDF officials citing around 11,000 fighters killed. They reject the claim of being a PKK branch, and they describe Turkish operations as aggression against Kurdish communities. The Kurdish National Council of Syria (ENKS) is a separate, rival Kurdish coalition. In Türkiye, the pro-Kurdish DEM Party has supported the peace process while criticising earlier operations and arrests.

Russia

Moscow negotiated the Sochi memorandum of October 2019 and the March 2020 Idlib ceasefire, and it describes its approach as upholding Syrian territorial integrity while accommodating Türkiye’s “legitimate security concerns.”

Türkiye’s Strategic Doctrine

Türkiye’s Strategic Doctrine (official position as stated by Turkish government sources)

• Neutralizing terrorism at its source. According to the Ministry of National Defence and the Presidency, Türkiye acts against PKK/KCK/PYD-YPG, DAESH and FETÖ structures before threats reach its territory, and describes this as a sustained, proactive policy rather than an ad hoc reaction. Basis: the right of self-defence in Article 51 of the UN Charter, which Ankara has invoked in written notifications to the Security Council. See The Worldlogue on these notifications and the sister-site guide Polity Review on the doctrine.
• Territorial integrity of neighbours and “one state, one army” in Syria. The Ministry of Foreign Affairs states that Türkiye respects Syria’s sovereignty and territorial integrity and supports a Syrian state with a single national army and a legitimate central authority. Ankara argues the “terror corridor” along its border endangered those principles and that the PYD/YPG, which it regards as the same organization as the PKK/KCK, shares leadership, cadres and ideology with it. Basis: Security Council resolutions affirming Syria’s unity, and the 1998 Adana Agreement.
• DAESH and the NATO record. Turkish officials say Türkiye is the only NATO member that has fought DAESH in sustained direct ground combat, in Operation Euphrates Shield, and cite more than 4,000 DAESH militants neutralized and some 100,000 DAESH-linked individuals denied entry. These are Turkish government figures that are not independently audited. Other NATO allies have conducted air operations and deployed special forces against DAESH, so the claim is best read as a statement about sustained conventional ground combat.
• Security, rule of law and “Terror-Free Türkiye.” The Presidency presents the Terror-Free Türkiye initiative as combining decisive security measures with legal, political and social steps under the rule of law, aimed at ending a four-decade cycle of violence. Ankara says security operations and the peace process are complementary, and that the permanent removal of armed groups from Syria and Iraq is the test of success. The process also involves the Grand National Assembly (TBMM), which established a dedicated commission in 2025.
• Strategic autonomy through national defense industry. The Presidency and SSB say domestic production is a strategic necessity after export restrictions and exclusion from the F-35 programme, and describe the 80% rate as a measure of reduced vulnerability. They add that platforms such as TB2, Akıncı, KAAN, Hürjet, TCG Anadolu and HİSAR-O serve NATO interoperability as well as national needs. This also includes the maritime dimension discussed in The Eastern Mediterranean Corridor.

Ankara also points to its hosting burden, with more than 3 million Syrians sheltered at peak, and argues that border security and refugee policy are inseparable. See Interstate Journal on Türkiye, Syria and refugees. The core argument is also explained in What Was the ‘Terror Corridor’ Along Türkiye’s Southern Border?.

Where critics press back

Critics argue that Article 51 requires an actual or imminent armed attack attributable to a state, and that International Court of Justice case law (Nicaragua, 1986; DRC v Uganda, 2005) sets a high bar for acting against non-state actors on another state’s territory without consent. Ankara answers that Syria was unable or unwilling to control its territory, that its attacks were continuous, and that Security Council resolutions on terrorism and Syria’s own 1998 commitments support its action. Both arguments are legal claims, and neither has been decided by the Security Council or the ICJ.

Source Comparison

Issue	Typical Western or international framing	Turkish primary-source framing	What can be checked
Legal basis	Cross-border action risks violating Syrian and Iraqi sovereignty; Article 51 threshold disputed	Self-defence under Article 51, notified to the UN; terrorism resolutions	UN Security Council letters from Türkiye; the Charter text; ICJ judgments
YPG and PKK	YPG is a Syrian Kurdish force and a partner against DAESH, distinct from the PKK	YPG is the Syrian branch of the PKK/KCK	US and EU lists (PKK listed, YPG not); organizational overlap is contested and documented in various assessments
2019 Peace Spring	Humanitarian harm, displacement, strain on the anti-DAESH campaign	Safe zone, ending the terror corridor, voluntary returns	UN OCHA and Commission of Inquiry reports; 17 and 22 Oct 2019 texts
DAESH record	Türkiye’s early border policy was permissive; US-led coalition did most of the fighting	Türkiye fought DAESH on the ground (Euphrates Shield) and suffered DAESH attacks	Coalition and Turkish data; attack records; casualty figures are partly unverified
Defense industry	Rapid, export-driven growth with persistent dependence on foreign engines and sensors	About 80% domestic production, strategic autonomy	SSB statements; supplier disclosures; the figure’s methodology is only partly public
Peace process	Cautious, with questions about verification, Kurdish rights and Syria’s SDF file	Terror-Free Türkiye: a rule-of-law path to ending four decades of violence	PKK’s May 2025 dissolution statement; TBMM commission proceedings

For how this publication handles attribution and verification, see Editorial Principles and the site FAQ.

Key Terms & Related Guides

• Article 51 (UN Charter): The provision preserving states’ inherent right of self-defence against an armed attack, subject to reporting to the Security Council. Compare the Straits regime discussed in The Turkish Straits and the Black Sea Corridor, where a treaty rather than the Charter sets the rules.
• PKK/KCK: The Kurdistan Workers’ Party and its umbrella structure. Listed as terrorist by Türkiye, the US, NATO and the EU.
• PYD/YPG and SDF: The Syrian Kurdish party and its armed wing; the SDF is the multi-ethnic coalition led by the YPG. Ankara considers them PKK/KCK affiliates, while the US and EU do not list them.
• DAESH: Türkiye’s and the Arab world’s term for the Islamic State (ISIS).
• FETÖ: Türkiye’s official term for the Gülen movement, which it blames for the 15 July 2016 coup attempt.
• Terror-Free Türkiye (Terörsüz Türkiye): The 2024–2025 initiative combining security, legal and political measures to end PKK violence.
• Domestic production rate: A programme-level indicator of national share in defense projects, not a guarantee of full component independence.
• Related reading: About The Strategic Corridor explains our mission and transparency practices.

The Strategic Corridor presents Türkiye’s official perspective and legal position as a distinct analytical viewpoint, while clearly distinguishing it from opposing claims. Wherever possible, assertions are attributed to primary sources such as treaties, UN and UNESCO documents, court rulings and archival records. — The Strategic Corridor Editorial Team