In 2016, the YPG-dominated Syrian Democratic Forces (SDF) pushed the Islamic State out of Manbij-a town on the western bank of the Euphrates-with support from the US-led coalition.
The YPG has received arms shipments and training from the USA, in a move that angered Turkey which considers the Kurdish forces to be a "terrorist group" that threatens its security.
The YPG is supported by United States with arms and training which angers Turkey.
Rebels said they had captured some 15 villages and seized 60 government fighters.
The YPG is the main element in a force that Washington has assisted with training, weapons, air support and help from ground advisers in the battle against ISIS.
But in November, Turkish officials said US President Donald Trump told them in a phone call that Washington would no longer supply arms to the YPG.
Warm and rainy for Thursday, snow and cold Friday
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Turkey also backed Syrian rebels when fighting broke out and has offered them extensive supplies, even after the USA backed away.
Both the US and Turkish interventions in Syria, however, have been dwarfed by that of Assad supporters Russian Federation and Iran.
Turkey has been fiercely opposed to Syrian President Bashar al-Assad during his country's six-year-old civil war but has recently been working with his allies Russian Federation and Iran for a political resolution to the conflict.
A year later, Turkey has grown frustrated with Russian Federation and Iran's continued backing of a recent Syrian military offensive that Ankara said threatened ongoing peace efforts. The regime is moving in Idlib.
The recent military escalation in western Syria has included an unprecedented attack by a squadron of drones on Russian military bases and has cast a shadow over Moscow's efforts to convene a Syria peace congress later this month.
The Russian Defense Ministry said drones targeting Russian facilities in Kmeimim and Tartus on January 6 had come "from the Muazzara settlement in the southwestern part of the Idlib de-escalation zone controlled by the armed forces of the so-called moderate opposition". A victory there would effectively sever a large pocket of the last remaining rebel region and give Syrian troops access to a highway linking Damascus and Aleppo.