Washington has ordered U.S. Special Operations troops not to wear the patches of Kurdish forces while advising them in Syria.
The order on May 27 follows shortly after protests from Turkey that the U.S. soldiers' actions were "unacceptable" to Ankara.
U.S. military spokesman in Baghdad Steve Warren said that while U.S. Special Operations Forces had historically and routinely worn the insignia of foreign troops they are working with, this case was not appropriate due largely to political sensitivities.
Turkish Foreign Minister Mevlut Cavusoglu said earlier on May 27 it was "unacceptable" for soldiers of a Turkish ally to use the patches of the Kurdish People's Protection Units (YPG) fighting the Islamic State extremist group.
Turkey views the YPG as an extension of the Kurdish Workers' Party (PKK), an armed insurgent group that it has fought for decades and is considered a terror organization by Turkey, the United States, and the European Union.
Photos of U.S. Special Operations Forces wearing the insignia surfaced this week, and Turkish leaders relayed their complaints to Washington.
The images emerged after Kurdish and Arab fighters launched a military campaign to drive IS militants back from territory north of their stronghold of Raqqa.
The U.S. military has some 300 troops in Syria to train and assist rebels in a noncombat role.
Based on reporting by AP and Reuters