Flying back from New York, where he addressed the UN General Assembly's annual meeting, President Recep Tayyip Erdogan told reporters on his plane that Turkey would participate in a US-led operation against the Islamic State (IS) stronghold of Raqqa, provided Syrian Kurdish fighters from the People's Protection Units (YPG) are not involved in it.

His remarks revealed once again that stopping advances in Syria by the YPG — whose fighters form the bulk of the US-supported Syrian Democratic Forces (SDF) — remains Ankara’s main priority.

Erdogan nevertheless continues to row against the current with regard to the YPG and its mother organization, the Democratic Union Party (PYD), both of which Ankara says are terrorist groups linked to the outlawed Kurdistan Workers Party (PKK).

Washington has consistently refused to accept Turkey’s position, making it clear that it considers the YPG to be its ally in Syria and the most viable force against IS. Much to Ankara’s annoyance, the United States is also continuing to arm the YPG as preparations to liberate Raqqa gather steam.