This week's violence brings with it a sense of deja vu. This time it's the result of more fighting between the Syrian army and Kurdish-led Syrian Democratic Forces or SDF. It reflects a deep rift between the two sides and many rounds of talks have so far failed to reach common ground. The SDF seeks a decentralized system of government - with areas under its control having a certain level of autonomy. But the government in Damascus wants to centralize power. So, what does it all mean for Syria's unity?