The Pentagon said on Wednesday that unilateral military action into northeast Syria by any party would be “unacceptable,” after Turkey said it would launch a new military operation in the region within days to target Kurdish militia fighters. Ankara and Washington have long been at odds over Syria, where the United States has backed the YPG Kurdish militia in the fight against Islamic State 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. Within hours of Turkish President Tayyip Erdogan’s announcement of the planned operation, the United States warned that any unilateral military action would undermine the shared interest of securing the border between Syria and Turkey in a sustainable way.“Unilateral military action into northeast Syria by any party, particularly as US personnel may be present or in the vicinity, is of grave concern,” Commander Sean Robertson, a Pentagon spokesman, said in a statement. “We would find any such actions unacceptable,” he added.Turkey has already intervened to sweep YPG fighters from territory west of the Euphrates in military campaigns over the past two years, but has not gone east of the river – partly to avoid direct confrontation with US forces.But Erdogan’s patience with Washington over Syria – specifically a deal to clear the YPG from the town of Manbij, just west of the Euphrates – seems to have worn thin. “We will start the operation to clear the east of the Euphrates from separatist terrorists in a few days. Our target is never US soldiers,” Erdogan said at a speech at a defence industry summit in Ankara.“This step will allow for the path to a political solution to be opened and for healthier cooperation.”Turkey has repeatedly voiced frustration about what it says are delays in the implementation of the Manbij deal, saying last month that the agreement should be fully carried out by the end of this year.The Pentagon said coordination and consultation between the United States and Turkey was the only way to address security concerns and that Washington was focused on working closely with Ankara.“We believe this dialogue is the only way to secure the border area in a sustainable manner, and believe that uncoordinated military operations will undermine that shared interest,” Robertson said.He added that while the United States was fully committed to Turkey’s border security, it also remained committed to working with the Syrian Democratic Forces, which includes Kurdish YPG fighters, to defeat Islamic State militants.Turkish and US troops began joint patrols near Manbij last month, but that cooperation has also been complicated as Turkey has shelled Kurdish fighters to the east of the Euphrates.Earlier this year, the US-backed Syrian Democratic Forces (SDF) temporarily suspended an offensive against Islamic State after Turkish shelling of northern Syria.Observation PostsThe Pentagon says it has about 2,000 troops in Syria.Last month, the United States said would establish observation posts on the border between Kurdish-held northern Syria and Turkey after Turkish cross-border shelling killed four Kurdish fighters.Three observation posts have now been set up, a US official told Reuters on Wednesday. The official said the positions were clearly marked and any force attacking them “would definitely know they are attacking the United States”.Turkish officials held talks in Ankara this week with the US special representative for Syria, Jim Jeffrey. An SDF military source said Jeffrey met the SDF leadership in northern Syria on Wednesday.Erdogan said Turkey was the victim of a “stalling tactic” over Manbij and that Islamic State no longer posed a threat in Syria.“Now, it’s time to realise our decision to disperse the circles of terror east of the Euphrates. The fact that we have deep differences in perception with the United States is no secret,” he said.Published in Daily Times, December 14th 2018.