Turkey’s Right to Self-Defense Requires Cross-Border Operations in Syria and Iraq

December 29, 2022

Since 2015, a total of 764 mortar attacks, rockets, and missiles have been fired from Syrian territory, targeting Turkey's populous southeastern cities.
A Turkish soldier keeps watch on a snow covered area on the Iraqi border of Derecik district of Turkiye's Hakkari on February 14, 2022. Photo by Anadolu Images


On November 13, a terrorist attack killed six civilians and injured 81 others on Istanbul’s crowded Istiklal Avenue. While the perpetrator was captured shortly after the terrorist attack, tens of people who were found to have connections to the attack were detained and most were arrested by court decision.

Individuals as important as the people involved in the attack provided evidence that the attack had been planned and carried out by the PKK/YPG terrorist organization. The statements by the arrested terror suspects clearly revealed that they had received instructions from the northern Syrian city of Manbij, or, in other words, from the PKK/YPG terrorist organization.

After the Istiklal Avenue attack, on November 20, Turkey launched a large-scale military air campaign against northern Iraq and northern Syria named “Operation Claw-Sword.” According to official data, 89 targets were destroyed, and many terrorists were killed in the first phase of the operation, which targeted shelters, bunkers, caves, tunnels, ammunition depots, and headquarters and training camps belonging to terrorists.

Turkey grounds it cross-border military operations on the legal principle of the right to self-defense; however, there are critics and statements that question the legitimacy of its operations. This makes it imperative to evaluate briefly the history of the county’s cross-border operations against terrorist organizations.

Cross-border operations against the PKK/YPG

Founded in 1978, the PKK is classified as a terrorist organization by the United States, the European Union, and many other states. In 1979, some of the initial leadership of the PKK first settled in Syria and Lebanon with the support of the Syrian government. As the PKK initiated its first terrorist acts in August 1982, it started also to settle in northern Iraq, using the opportunity created by the Iran-Iraq War of 1980-1988. The PKK established camps in the Kandil Mountains, close to the Iran-Iraq border in northern Iraq, which became its main headquarter and served as a base to attack Turkey.

Since 1983, Ankara has had to initiate cross-border operations against the PKK to fight back terrorist attacks coming from cross-border bases. The legal bases for Turkey’s operations have periodically changed from the expressed or tacit consent of the Iraqi governments to the right to self-defense. Turkey has carried out a large number of cross-border military operations; some followed Iraqi approval, while others were in hot pursuit and based on the right to self-defense.

The latest of these operations is Operation Claw which started on May 27, 2019. The operation is ongoing and so far has included Operation Claw 2, which began on May 27, 2019; Operation Claw 2, which began on July 13, 2019; Operation Claw 3, which began on August 23, 2019; Operation Claw-Eagle, which began on June 15, 2020; Operation Claw-Tiger, which began on June 17, 2020; Operation Claw-Eagle 2, which began on February 10, 2021; and Operations Claw-Lightning and Claw-Thunderbolt, which have continued throughout 2022. It has been stated that via these operations more than 830 terrorists have been neutralized, 1,281 weapons have been seized, and 1,407 caves and 1,812 handmade explosives have been destroyed.

In recent years, Turkey has had to direct some of the cross-border operations to northern Syria due to the new developments caused by the Syrian conflict. These operations include Operation Euphrates Shield (August 24, 2016 – March 29, 2017, in Jarablus and Al-Bab, Aleppo, Operation Olive Branch (January 20, 2018 – March 24, 2018 in Afrin and Aleppo), Operation Peace Spring (October 9, 2019 – October 18, 2019 in Rasulayn and Tel Abyad), and Operation Spring Shield (February 27, 2020 – March 5, 2020 in Idlib).

The legal basis of Operation Claw-Sword

Turkey’s most recent cross-border military operation named “Operation Claw-Sword” targeted the Kandil, Asos, and Hakurk regions in northern Iraq including the Sinjar region. In northern Syria, the military operation further targeted places in the regions of Ayn al-Arab, Tel Rifat, Cizire, and Malikiye (Derik). Karacok Mountain, Derbesiye, Ayn Issa, Minniğ Airport and Maranez were also targeted in the following stages.

Specifically, the operations targeted the terrorist group’s shelters, bunkers, caves, tunnels, ammunition depots, headquarters, and training camps that posed a direct threat to Turkey’s security.

The legal aspect of Turkey’s cross-border operations

Some objections have been voiced against Turkey’s Operation Claw-Sword, leading to the need for a clarification of Turkey’s legal stance.

Article 51 of the UN Charter regulates the right to self-defense. The article stipulates that the right to self-defense is natural; in other words, every state has this right by nature. This right comes into effect in case of an armed attack. A state’s right to self-defense can be exercised either alone or together with other states which come to the help of the state under attack. Until the UN Security Council takes measures to protect international peace and security, all states can exercise this right.

Although not expressed in the article, proportionality is an element of the right to self-defense: a response should be in proportion to the attack and not exceed the boundaries necessary to stop and/or eliminate the threat.

The decision of the International Court of Justice (ICJ) in the case concerning “Military and Paramilitary Activities in and against Nicaragua” (Nicaragua v. United States of America) established that a state must be subject to an “armed attack” in order for the right of self-defense to arise.

The court held that an armed attack is not only limited to “action by regular armed forces across an international border,” but also the “sending by or on behalf of a State of armed bands, groups, irregulars or mercenaries, which carry out acts of armed force against another State of such gravity as to amount to (inter alia) an actual armed attack conducted by regular forces,” or “its substantial involvement therein.”

Therefore, armed attacks by irregular groups give rise to the right of self-defense, as long as they are categorized as “armed attacks” rather than “frontier incidents.”

The court further emphasized that the description contained in Article 3, paragraph (g) of the Definition of Aggression annexed to General Assembly Resolution 3314 (XXIX) may be taken to reflect customary international law. That is to say that the legal approach concerning the use of the right of self-defense is legally binding to all states as customary rule of international law.

The PKK/YPG’s constant attacks on Turkey from northern Iraq and northern Syria exceed the level of border friction and can be classified as “armed attacks” carried out by regular armed forces. According to the officially announced figures, since 2015, a total of 764 mortar attacks, rockets, and missiles have been fired from Syrian territory, targeting the populous cities of Hatay, Gaziantep, Kilis, Şanlıurfa, Mardin, and Şırnak in southeast Turkey. Thirty-two Turkish citizens have been killed and 261 people have been injured in these attacks. In a very recent attack, two civilians lost their lives and six people were injured, two of them seriously, in a rocket attack carried out against the Turkish town of Karkamış from the north of Syria.

Apart from these attacks and murders, 173 civilians and 153 security guards have lost their lives in 87 separate terrorist acts by the PKK and related organizations inside the borders of Turkey within the last seven years.

Statements and images from Turkey’s most recent cross-border military operations reveal that the operations specifically target the terrorist camps, shelters, and related compounds.

Turkey’s right to self-defense requires it to conduct cross-border military operations in northern Syria and northern Iraq. This right emanates and is regulated by Article 51 of the UN Charter.

Yücel Acer is currently working as Professor of International Law at Ankara Yıldırım Beyazıt University, Turkey. Acer is the author of numerous books such as "The Aegean Maritime Disputes and International Law", "The Crime of Aggression in International Law", and "Asylum Strategy of Turkey from the Global and Regional Perspectives"