The Wall Street Journal had reported Sunday that as talks with Turkey, US-backed Kurdish forces and European allies have failed to produce a deal on a "safe zone" in northeastern Syria, the US now intended to keep working with Kurdish fighters in the country.

It quoted US officials as saying the plan could see up to 1,000 US forces spread across the country.

"A claim reported this evening by a major U.S. newspaper that the U.S. military is developing plans to keep nearly 1,000 U.S. troops in Syria is factually incorrect," General Joseph Dunford, chairman of the Joint Chiefs of Staff, said in a statement.

"There has been no change to the plan announced in February and we continue to implement the President's direction to draw down U.S. forces to a residual presence."

But he added the US was continuing to "conduct detailed military planning with the Turkish General Staff to address Turkish security concerns along the Turkey-Syria border."

"Planning to date has been productive and we have an initial concept that will be refined in the coming days," he said.

"We are also conducting planning with other members of the Coalition who have indicated an intent to support the transition phase of operations into Syria."

President Donald Trump had abruptly announced in December the immediate and complete withdrawal of the 2,000 US troops deployed in northeastern Syria, declaring victory against the Islamic State group. The decision prompted his defense secretary Jim Mattis to quit.

Then, under pressure from Congress and the Pentagon, he agreed to leave a residual force of some 200 US troops, which he wants to be reinforced by allies in the anti-IS coalition.

An objective of the international force is to guarantee the security of its Syrian Kurd allies. Turkey, a NATO member, views the Kurdish combatants as terrorists, and the Europeans fear they would be vulnerable if Ankara launched an offensive.