On January 22, 2018, the Permanent Mission of Turkey to the United Nations sent a letter to the UN Security Council laying out its justification for its military intervention against the Kurdish-populated region of Afrin in Syria (Operation Olive Branch) as self-defense in terms of Article 51 of the UN Charter. In the letter, Turkey states that its national security of “has been under direct threat from the Syria-based terrorist organizations, among which Deash and the PKK/KCK Syria affiliate, PYD/YPG, are at the top of the list,” and that “[t]he recent increase in rocket attacks and harassment fire directed at Hatay and Kilis provinces of Turkey from the Afrin region of Syria, which is under the control of the PKK/KCK/PYD/YPG terrorist organization, has resulted in the deaths of many civilians and soldiers and has left many more wounded.” The letter goes on to state that Turkey initiated a military operation on January 20, 2018, “aimed at ensuring our border security, neutralizing terrorists in Afrin and saving the brotherly Syrians,” and that it “was essential in order to ensure the border security of Turkey and our national security based on our right of self-defence, as defined in Article 51 of the Charter, but also within the context of the responsibility attributed to Member States in the fight against terrorism, including through Security Council resolutions 1373 (2001), 1624 (2005), 2170 (2014) and 2178 (2014).”