The risk of confrontation with the medley of different ground forces — both state-led and proxy — is undoubtedly higher than it was several weeks ago.

Convoys moving through contested territory and aircraft making repeated landings all might contribute to an accidental confrontation or a staged attack, especially from any Islamic State leftovers that might want to take advantage of the sudden withdrawal.

One of the biggest risks to the remaining American troops as they pull back will most likely be attacks from a Turkish-backed Syrian militia called the Free Syrian Army, which has spearheaded the Turkish offensive in many places along the border. Those troops are supported by Turkish Army artillery and mortar fire, and Turkish Air Force strikes.

American officials say these Turkish-backed militia are less disciplined than regular Turkish soldiers, and deliberately or inadvertently have fired on retreating American troops.