The United States scrambled Friday to avert a rift with its ally Turkey after AFP pictures revealed US commandos operating in Syria wearing the insignia of a Kurdish militia branded a terror group by Ankara.
The Pentagon announced that special operations troops in northern Syria would henceforth stop wearing the badge of the YPG guerrillas, after Turkey accused the United States of "unacceptable" behavior.
It had long been public knowledge that around 200 US commandos are in northern Syria helping local militia target the Islamic State extremist group's de facto capital Raqa and guiding in coalition air strikes.
But the sight, revealed by AFP photographs, of US special forces sporting the YPG badge proved a step too far for Ankara, which regards it as a branch of the Turkey-based "terrorist" PKK guerrilla movement.
Foreign Minister Mevlut Cavusoglu accused the United States of "hypocrisy" and "double standards" and said the American soldiers might just as well have worn the logo of Al-Qaeda, the IS group or Boko Haram.
The State Department played down the spat, insisting that Washington and Ankara remain close partners in the broader fight against the Islamic State, despite disagreements about the role of the YPG.
"We understand Turkey's concerns, let me make that clear, and we continue to discuss this as well as other concerns Turkey has," spokesman Mark Toner said.
"With respect to Turkey's comments about these photos we've been very clear... about our belief that the YPG is not connected to the PKK," Toner said.
"And we're going to continue to support them with our assist and support operation," he said.
Despite the US military's determination to continue to work with the YPG, which provides the bulk of the so-called "Syrian Democratic Forces" fighting the IS group, the Pentagon said the badges would be removed.
"Wearing those YPG patches was unauthorized and inappropriate, and corrective action has been taken," Baghdad-based military spokesman Colonel Steve Warren told Pentagon reporters.
While it is not unusual for US special operations forces to wear the insignia of partner forces, Warren said in this case it was inappropriate, given the "political sensitivities" around the issue.
Ankara accuses the YPG of carrying out attacks inside Turkey and of being the Syrian branch of the Kurdistan Workers' Party (PKK), which is fighting a three-decade-old insurgency against the Turkish state.
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The United States has blacklisted the PKK as a "foreign terrorist organization" but regards its Syrian-based sister group the PYG as a useful ally in the face of the Islamic State threat.
- 'Two different wars' -
Soner Cagaptay, director of the Turkey Research Programme at the Washington Institute, told AFP the dispute highlighted a "long-term problem facing the US-Turkish relationship".
He said Turkey and the United States are "effectively fighting two different wars in Syria", with Washington focused on the fight against IS and Turkey working to defeat President Bashar al-Assad's regime.
Charles Lister, a senior fellow at the Middle East Institute in Washington, said US officials had described the leftist PYG as linked to the PKK until 2014, when they started working with it.
"These guys are wearing the badge, whether we like it or not, of the Syrian wing of a terrorist organization," he said of the US commandos.
"The US government has designated it as such. And they are wearing the badge and not only that, it's got the red star of Communism on it," he told AFP.
The AFP photographer saw US forces on the ground in northern Syria helping the Kurdish-Arab Syrian Democratic Forces (SDF) in a major offensive against IS in its Raqa province stronghold.
Ozgur Unluhisarcikli, director of the office of the German Marshall Fund of the United States in Ankara, said the dispute is "poisoning" US-Turkey relations.
"The US sees the YPG as a local actor who can be cooperated with in Syria. Whereas Turkey, rightfully, sees it as the PKK's partner in Syria," he told AFP.
- 'YPG unreliable' -
Cavusoglu complained that, in private talks with President Barack Obama and Secretary of State John Kerry, the United States had admitted to him that the YPG "are not reliable".
"And then they wear the badges of the terrorist organisation responsible for the last two attacks in Ankara," he declared.
Turkey blamed the YPG for attacks in the capital this year that killed dozens, though they were claimed by a PKK splinter group, the Kurdistan Freedom Falcons (TAK).