By Hilmi Tunahan Karakaya and Erdal Turkoglu

HATAY, Turkey

Turkish security forces on Saturday hit several PYD/PKK targets in the besieged Syrian border town of Afrin in order to prevent a "terror corridor" from forming along Turkey's borders.

Turkish army launched at least 15 rounds of artillery fire, targeting the terror nests of the terror organization in Afrin, a northern district of the Aleppo province.

On Saturday, President Recep Tayyip Erdogan announced that a ground operation in Syria's Afrin had been launched.

Addressing the ruling Justice and Development (AK) Party's sixth annual provincial congress in western city of Kutahya, Erdogan said an operation in Manbij in Syria will come after Afrin because "promises made to Turkey have not been kept."

Military vehicles and work machines sent to reinforce the troops stationed at the Syrian border were already in Turkey's Hatay province.

Turkey has long protested the U.S. support for the PYD -- the Syrian offshoot of the terrorist PKK -- and its military wing the YPG.

Washington has called the terrorist group a "reliable ally" in its fight against Daesh in Syria even though its mother organization, the PKK, is listed as a terrorist group by Turkey, the U.S., and the EU, having waged a terror campaign against Turkey for more than 30 years, killing nearly 40,000 people.