Turkey had in recent days sent dozens of military vehicles to the border area and readied pro-Ankara Syria rebels in preparation for the operation against the People's Protection Units (YPG) militia which Turkey deems to be a terror organisation.
Turkey has long protested the USA support for the PYD - the Syrian offshoot of the terrorist PKK - and its military wing the YPG. The Kurds were Washington's most trusted force in the USA -led campaign to drive Islamic State extremists from Syria, but the Turkish government says they work hand-in-hand with PKK militants who have been battling for autonomy in Turkey's southeast since the 1980s.
The US plans to train about 30,000 personnel to help prevent infiltration by IS militants across the Turkish and Iraqi borders and the River Euphrates, which effectively divides Kurdish- and Syrian government-held regions. It is the US -led coalition's chief ally in the campaign against the Islamic State in Syria.
Throughout most of the almost seven-year-old Syrian civil war, Turkey has been one of the strongest opponents of Assad, joining the United States in supporting rebels fighting to overthrow him.
Rather, he said, the USA military will provide training to local elements to help secure areas that were liberated from the Islamic State, with us assistance, over the past three years.More news: Colbert Calls Out Homeland Security Secretary for Dodging Trump's "Shithole" Remarks
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Washington now is working with the SDF to create a border security force in northern Syria, much to the dismay of Ankara.
The Syrian Foreign Ministry was responding yesterday to a speech by the US Secretary of State, Rex Tillerson, on Wednesday in which he signalled that US forces would stay in parts of Syria indefinitely. He was quoted saying, "Tomorrow, (or) the day after, (or) within a short period, we will get rid of terror nests one-by-one in Syria starting with Afrin and Manbij" in northern Syria.
"This will be followed by Manbij", he added, referring to another Kurdish-controlled Syrian town to the east.
Turkey will not hesitate to start military operations in Syria's Afrin city and kill all terrorists there, Turkish Defense Minister Nurettin Canikli said on January 19.
Moscow has been calling on the warring parties to exercise restraint.
"Such a responsible behavior will lead to the desired result in finding a resolution for the Syrian crisis", the Democratic Union Party said in a statement. Turkey is working with both Russian Federation and Iran to broker a peace deal to end the war.