Kurdish officials familiar with the situation are expressing concern about on ongoing Turkish military buildup in northern Syria, believing that Turkey is position forces around the Afrin District in Aleppo Province, a strategic area held by Kurdish YPG forces, is going to soon be attacked.
Turkey has launched airstrikes against Afrin in the past, but with the YPG so heavily focused on the invasion of the ISIS capital city of Raqqa, they don’t have the most substantial defense left behind in their own territory, and are concerned an attack would oblige them to shift forces away from Raqqa, losing the momentum they have in the area in favor of defending against Turkish forces.
Turkey hasn’t said anything about any imminent attacks, but has long threatened moves against the YPG as a “terrorist” group. The US has also confirmed they are “aware” of the Turkish troop movements, but declined to speculate on what they might portend.
The timing would be strange, as Turkey appeared placated by a US promise to disarm the YPG as soon as ISIS is defeated. They have, however, long resented the US decision to back the Kurds over them in attacking Raqqa, as Turkey suggested they and the US should launch the invasion without the Kurds involved.