Joint Chiefs Chairman Gen. Joseph F. Dunford called the reported new force numbers "factually incorrect," insisting there has been no change to the planned 400 troops the White House announced last month.

"Further, we continue to conduct detailed military planning with the Turkish General Staff to address Turkish security concerns along the Turkey-Syria border," Dunford said in a statement. "Planning to date has been productive and we have an initial concept that will be refined in the coming days."

The Wall Street Journal reported earlier in the day that ongoing negotiations between the U.S., Turkey and European allies over a potential safe zone in northeastern Syria -- a key element of Trump's departure plan -- have yet to lead to a conclusive agreement.

The newspaper said the U.S. is now seeking to continue its cooperation with the YPG-led SDF despite Turkey's warnings that it will conduct a cross-border operation against the Kurdish-led forces.

That could lead to as many as 1,000 American troops remaining in northeastern Syria, the newspaper reported citing anonymous American officials.

Reporter’s code: 50101