On 9 October 2019, the Turkish Armed Forces (TAF) and the Syrian National Army (SNA) launched an offensive against the Syrian Democratic Forces (SDF) and later it involved the Syrian Arab Army (SAA) in northern Syria. It was code-named the Operation Peace Spring (Turkish: Barış Pınarı Harekâtı) by Turkey.
On 6 October 2019, the Trump administration ordered American troops to withdraw from northeastern Syria, where the United States had been supporting its Kurdish allies. The military operation began on 9 October 2019 when the Turkish Air Force launched airstrikes on border towns. The conflict resulted in the displacement of over 300,000 people and has caused the death of more than 70 civilians in Syria and 20 civilians in Turkey. Human rights violations have also been reported. Amnesty International stated that it had gathered evidence of war crimes and other violations committed by Turkey and Turkish-backed Syrian forces who are said to "have displayed a shameful disregard for civilian life, carrying out serious violations and war crimes, including summary killings and unlawful attacks that have killed and injured civilians".
According to Turkish President Recep Tayyip Erdoğan, the operation was intended to expel the SDF—designated as a terrorist organization by Turkey "due to its ties with the Kurdistan Workers Party (PKK)", but considered an ally against ISIL by the Combined Joint Task Force – Operation Inherent Resolve—from the border region as well as to create a 30 km-deep (20 mi) "safe zone" in Northern Syria where some of the 3.6 million Syrian refugees in Turkey would resettle. As the proposed settlement zone is heavily Kurdish demographically, this intention has been criticized as an attempt at ethnic cleansing, a criticism rejected by the Turkish government who claimed they intended to "correct" the demographics that it alleges have been changed by the SDF.
The Turkish operation was met with mixed responses from the international community, including condemnations as well as support for the operation for the settlement of refugees in Northern Syria. Although Turkey claimed self-defense, according to international law experts it is an illegal use of force. While originally acknowledging Turkey's "right to defend itself", on 15 October, Russia hardened its position against the operation and deployed troops. Ten European nations and Canada imposed an arms embargo on Turkey, while the U.S. imposed sanctions on Turkish ministries and senior government officials in response to the offensive in Syria. The Assad-led Syrian government initially criticized the SDF for the Turkish offensive, accusing it of separatism and not reconciling with the government, while at the same time also condemning the foreign invasion of Syrian territory. However, a few days later, the SDF reached an agreement with the Syrian government, in which it would allow the Syrian Army to enter the SDF-held towns of Manbij and Kobanî in an attempt to defend the towns from the Turkish offensive. Shortly thereafter, Syrian state broadcaster SANA announced that Syrian Army troops had started to deploy to the country's north. Turkey and the SNA launched an offensive to capture Manbij on the same day.
On 17 October 2019, U.S. Vice President Mike Pence announced that the U.S. and Turkey agreed on a deal in which Turkey would agree to a five-day ceasefire in Syria in return for a complete withdrawal by the SDF from its positions on the Syria-Turkey border. On 22 October 2019, Russian President Vladimir Putin and Turkish President Recep Tayyip Erdoğan reached a deal to extend the ceasefire by 150 additional hours if the SDF would move 30 kilometers away from the border, as well as from Tal Rifaat and Manbij. The terms of the deal also included joint Russian–Turkish patrols 10 kilometers into Syria from the border, except in the city of Qamishli. The new ceasefire started at 12pm local time on 23 October. The captured area remains part of the Turkish occupation of northern Syria.