ANKARA, Jan. 20 (Xinhua) -- Turkish President Recep Tayyip Erdogan announced on Saturday the military operation in Syria's Afrin has "actively" started.

"The Afrin operation has actively begun on the field. The Manbij operation will follow," he said during a televised speech in the Aegean province of Kutahya.

Erdogan said that Turkey is determined to ensure its national security and to clear its borders of the People's Protection Units (YPG), which is considered as the Syrian affiliates of the Kurdistan Workers' Party (PKK) by Ankara.

The PKK, listed as a terrorist organization by Turkey, the European Union and the United States, has been conducting armed violence against Ankara since July 2015 after a brief reconciliation period.