pTurkish army tanks have fired shells across the Syrian border for a fourth day at Kurdish YPG forces. They've been grabbing land that may otherwise fall into the hands of the Assad regime or Islamist radicals, both enemies of Ankara but your enemies' enemies are not necessarily your friends. President Erdogan is angry over ties between the Syrian Kurds and enemy number three, the separatist PKK movement it's fighting in southeastern Turkey. And now Russia is looming as a fourth enemy...pbr Produced by Charles WENTE, François WIBAUX and Christopher DAVIES.