A spokesman for the coalition said it "has begun the process of our deliberate withdrawal from Syria." The spokesman added that, to protect security, the coalition would not provide details on troop movements.
There are about 2,000 U.S. troops in Syria.
The Syrian Observatory for Human Rights reports that the withdrawal began late Thursday. It says about 10 armored vehicles and other equipment arrived at a U.S. base in al-Rmelan, in al-Hasaka province. The group also reports that coalition reinforcements arrived at different bases Thursday. A source confirmed that information with VOA.
U.S. national security advisor John Bolton said Friday that talks between U.S. and Turkish military officials will continue next week. The two sides are trying to reach agreement about Kurdish fighters allied with the United States against Islamic State forces in Syria.
Earlier this week, Bolton's calls for the protection of the YPG Syrian Kurdish militia as a condition for a Syrian withdrawal angered Turkey. Turkish President Recep Tayyip Erdogan then canceled a planned meeting with Bolton.
The YPG is an important ally in the U.S. war against the Islamic State. Turkey, however, considers the YPG a terrorist group linked to a rebellion in Turkey.
In his comments, Bolton had said that he, President Donald Trump and Secretary of State Mike Pompeo held the understanding that Turkey had agreed "not to harm the Kurds who had fought with us against ISIS."
But Bolton also said the United States was still seeking some guarantees of that agreement through "protocols and procedures."
Erdogan warned that preparations were complete for a military operation against the YPG.
"We will very soon mobilize to eliminate the terrorist organization in Syria," Erdogan said.
He added, "If there are other terrorists who would attempt to intervene in our intervention, then it is our duty to eliminate them as well."
Turkish forces have been deploying for weeks along the Syrian border.
I'm Caty Weaver.