Turkey summoned the US ambassador on Tuesday after a State Department spokesman said Washington did not regard Syria's Kurdish Democratic Union Party (PYD) as a terrorist organisation, a Turkish foreign ministry official said.
Ankara sees the PYD as a sister arm of the Kurdistan Workers Party (PKK), which is fighting for Kurdish autonomy in southeastern Turkey and is classed as a terrorist organisation by Turkey, the United States and the European Union. Washington supports the PYD in its struggle against Islamic State militants in Syria.