The Pentagon said on December 12th that unilateral military action in northeast Syria by any party would be “unacceptable,” in a statement that came after Turkish President Recep Tayyip Erdogan said that Turkey would launch a new military operation in the region.
"Unilateral military action into northeast Syria by any party, particularly as US personnel may be present or in the vicinity, is of grave concern," Reuters cited the Pentagon spokesman, Commander Sean Robertson, as saying. "We would find any such actions unacceptable," he added.
Turkey, for its part, is looking to target Kurdish militia fighters it perceives as terrorists. Within hours of Erdogan's announcement of the planned operation, the US warned that any unilateral military action would undermine the shared interest of securing the border between Syria and Turkey.
Ankara and Washington have long been at odds over Syria, where the US backs the YPG Kurdish militia in the fight against ISIS insurgents. Turkey says the YPG is a terrorist organisation and an extension of the outlawed Kurdistan Workers Party (PKK), which has waged an insurgency against the state in southeastern Turkey for 34 years.