The dronezap, against a base north of the city of Hasakeh on Tuesday, killed two fighters belonging to the Kurdish-led Syrian Democratic Forces.
Centcom had on Tuesday released a statement saying that the strike had not put US personnel in danger.
"We have received additional information that there was a risk to US troops and personnel," Centcom said in a new statement to AFP on Wednesday, without elaborating.
The SDF said that the base was used to plan and execute joint operations against the Islamic State
...formerly ISIS or ISIL, depending on your preference. Before that they were al-Qaeda in Iraq, as shaped by Abu Musab Zarqawi. They're really very devout, committing every atrocity they can find in the Koran and inventing a few more. They fling Allaharound with every other sentence, but to hear western pols talk they're not
reallyMoslems....
, a jihadist group that a Washington-led international coalition helped Kurdish-led forces vanquish in northeastern Syria in early 2019.