The Turkish government said it was "unacceptable" that US troops are donning the insignia of the YPG, the Kurdish movement in northern Syria, which it considers a terrorist organisation.
The photographs were published by AFP on Thursday, and picture US soldiers near Raqqa, with shoulder patches of the YPG insignia.
“To those who say they don’t consider the YPG to be the same as these terrorist groups, this is our response,” Foreign Minister Mevlut Cavusoglu said. “This is applying double standards, this is being two-faced.”
On Thursday, the US Department of Defense said that " special operations forces when they operate in certain areas do what they can to, if you will, blend in with the community to enhance their own protection, their own security".
However another US officials later said the patches were "unauthorised".
“Wearing those YPG patches was unauthorized and inappropriate, and corrective action has been taken,” Colonel Steve Warren, the spokesman for Operation Inherent Resolve (OIR) who is based in Baghdad, told reporters at the Pentagon. “We have communicated as much to our military partners and military allies in the region.”