The US-backed coalition of Kurds and Arabs of the Syrian Democratic Forces (SDF) have begun their long-awaited assault on the Islamic State’s self-proclaimed caliphate in Raqqa. The forecast for the battle has it that it will be long and costly as the IS fighters are cut off from any support.

But the government of Turkey released an ominous warning that they’ll be watching the SDF for any aggression to their own interests. Turkey considers the Kurds terrorists in their country which makes the entire alliance against the IS on shaky ground.

On Tuesday, Prime Minister Binali Yildrim said Turkey would act immediately should any perceived threats arise from the Syrian Democratic Forces’ operations to recapture the city of Raqqa from the so-called “Islamic State” (IS).

Yildrim made his remarks in Ankara to deputies from President Recep Tayyip Erdogan’s ruling Law and Justice Party on the same day that the SDF launched an attack on the IS stronghold from the east, north and west.