Speaking today at the opening of an Ankara factory, Erdogan said it was his Government's duty "to drown this terrorist force before it is born".
Erdogan urged all friendly countries and allies of Turkey not to stand in the way of Ankara in its fight with terrorists and assassins.
Meanwhile, the Assad government, backed by Russian Federation and Iran, has made great strides over the past two years in defeating a range of opponents, restoring control over almost all of Syria's main cities.
Backed by the US-led coalition's air strikes, advisers and weapons, the SDF has ousted IS from swathes of territory in the east and north, including IS bastion Raqa.
The SDF captured Raqqa, the de facto capital of IS, late a year ago, and the Syrian army captured the eastern city of Deir al-Zour, another IS bastion nearly in the same timeframe. Since then, SDF fighters have been advancing south-eastwards along the Euphrates river valley.
The Syrian government in Damascus has declared the U.S.an illegal occupation force and its SDF allies as "traitors". Washington's support for Kurdish-dominated forces in Syria has long angered Ankara.
The force will comprise 30,000 people and established over several years.
In comments to the Reuters news agency, the coalition said the recruits would operate under SDF command and that around 230 individuals were undergoing training in its inaugural class. Policy decisions like this, which are made without taking into consideration that the PYD, the PKK's Syrian branch, does not represent the Syrian Kurdish community and puts the Kurdish people's safety and well-being in the Middle East at risk.
Erdogan called on Washington to cease its cooperation with the YPG.
The U.S. -led coalition is now training Syrian militias and plans to establish a new border force together with the Kurdish-led opposition fighters, consisting of 30,000 personnel over the next several years, according to the coalition.
"Syria strongly condemns the U.S. announcement on the creation of militias in the country's northeast, which represents a blatant attack on the sovereignty and territorial integrity and unity of Syria, and a flagrant violation of worldwide law", said the source, cited by state news agency SANA.
"The Turkish Armed Forces will resolve the Afrin and Manbij issue as soon as possible". Troops deployed at the border were already hitting YPG positions inside Afrin with heavy artillery, he noted.
The Syrian government says what the U.S. administration has done comes in the context of its destructive policy in the region to fragment countries and impede any solutions to the crises.
Erdogan said Turkey had completed preparations for an operation in Kurdish-held territory in northern Syria.
The source warned that Damascus considered any Syrian fighting for militias sponsored by the USA to be "a traitor to their people and nation".
Turkey has reacted sharply to news of the border force, saying it would "legitimise a terror organisation".