In January 2018, the Turkish military began an intervention in the Afrin region of Syria, code-named by Turkey as Operation Olive Branch (Turkish: Zeytin Dalı Harekâtı). The offensive is against the Kurdish Democratic Union Party in Syria (PYD), its armed wing People's Protection Units (YPG), and Syrian Democratic Forces (SDF) positions surrounding the Syrian city of Afrin. Turkey also says it is fighting the ISIL. Afrin and the surrounding area is claimed by the Democratic Federation of Northern Syria as the Afrin Region. It is the first major military operation by Turkey in Syria since Operation Euphrates Shield.
Turkish President Recep Tayyip Erdoğan said on the same day that the operation in Afrin would be followed by a push in the northern town of Manbij, which the US-backed Kurdish forces captured from ISIL in 2016. The YPG announced that it would protect the people of Afrin and respond to the Turkish army. Dozens of civilians have been killed since the operation started.
From Wikipedia