It might just be a domestic political stunt to generate fear and suspicion.
No the Kurds have been talking very loudly about how they're going start their offensive on Raqqa any day now for the last month. Of course with the Kurds not being braindead, it likely means that the Kurds will attack on another front. But ISIS can not ignore the threat, because they risk if they don't move troops to Raqqa that the Kurds will attack it. Of course those troops are moved away from other front allowing the Kurds to attack on those and SAA to continued their offensive against ISIS in the south.
