The problem in Syria and also Isis is no longer a problem for the Middle Eastern countries, but it affects people on a global spectrum. Turkey president Recep Tayyip Erdogan met with president Barack Obama last week and Isis, PYD and PKK were subjects of their conversation. The US and Turkey see eye to eye when it comes to the groups I mentioned above. According to reports the PYD and PKK are working together.
The facts on the ground support Turkey's claims: In Nusaybin, where the Turkish security forces have been cracking down on PKK networks, the terrorists have been receiving support from al Qamishli - a PYD-controlled town across the border. Meanwhile, PKK militants have been targeting security forces with IEDs - a skill that the PYD learned f from DAESH. To make matters worse, the authorities discovered that at least two PKK- affiliated suicide bombers, who blew themselves up in Ankara, had previously received training among the PYD ranks.
They had been a little friction between the US and Turkey foreign policy. The US supported PYD because they believed it was their ally fighting against Daesh. However, it turns out that PYD was fighting with other intentions (to get their own land) and the Turkish government was upset that Washington did not label PYD as a terrorist organization.