The U.S. military has about 2,000 U.S. troops in Syria across a number of bases, mostly in the northeast. The troops are working with local forces to prevent a resurgence of Islamic State, which in 2014 seized large swathes of Iraq and Syria but was later pushed back.

The departure would return force levels to where they had been for years, after the U.S. and its allies waged a multiyear campaign to defeat ISIS.

The end of the Assad era has reduced some threats, but the Islamic State has shown renewed strength in the country.