Eighteen Syrian regime forces and members of the Kurdish Asayish police forces were killed on Saturday in clashes that erupted in the center of the city of Qamishli, northeastern Syria, where both sides share power.
Experts said Saturday's confrontation was a "test of force," particularly since regime forces control two security squares in Qamishli and Hasaka, east of the Euphrates River, which is under the control of US-backed Syrian Democratic Forces (SDF).
Reports said at least 11 Syrian security personnel were killed after their patrol allegedly refused to stop at an Asayish checkpoint. Seven Kurds were killed in ensuing clashes.
In a statement Saturday, the Asayish said as the regime forces passed through the checkpoint, they "attacked our forces with light and medium weapons," promoting retaliation from the Kurdish forces.
Kurds control most of Qamishli, but regime fighters and allied militiamen hold part of the city and its airport.
Meanwhile, Russian warplanes and Syrian regime helicopters launched on Saturday their heaviest attacks on Idlib, a day after a trilateral Russian-Turkish-Iranian summit in Tehran failed to reach a roadmap on the northwest province.
Russian warplanes launched around 60 strikes in less than three hours on towns and villages in the countryside of southern and southeast Idlib.
"Russian warplanes launched 68 raids on areas in Khan Shaykhun, al-Lataminah and places in the areas of al-Tamanah, Hish, al-Serj, and Abdeen, in conjunction with dropping more than 19 barrel bombs on areas in Khan Shaykhun, al-Halba, Tal Aas, Babulin, al-Lataminah, al-Sayyad, and Kafr Zita in the southern and southeastern countryside of Idlib, and in the northern countryside of Hama," the Syrian Observatory for Human Rights said.
In a twitter message, Turkish President Recep Tayyip Erdogan said Turkey would neither watch from the sidelines nor participate in such a game "if the world turns a blind eye to the killing of tens of thousands of innocent people in Syria."