Russia's military intervention in Syria has jolted NATO and provoked frustration in Washington. On Wednesday, Russia launched cruise missiles from warships in the Caspian Sea.
Russian jets have twice entered Turkish airspace, according to NATO, which has disputed Russia's account of an accidental incursion during action in Syria.
Turkey has vowed to step up its campaign against the outlawed PKK. The collapse of its cease-fire with the PKK has complicated the US-backed campaign against the self-proclaimed Islamic State.
The outlawed PKK separately attacked a Turkish military brigade in southeast Turkey. Analysts say Turkey is prioritizing air strikes against Kurdish militants over strikes against the self-styled Islamic State.
One of two shooters who fired on US Consulate in Istanbul is in custody, and far-left groups claims responsibility. Ten hurt in car-bomb attack at police station.
Even as the US and Turkey agree on trying to drive the Islamic State away from the Syrian side of the border with Turkey, there are as many agendas as there are players trying to shape the conflict.
Turkey has long sought a buffer zone in northern Syria. Critics say it is exploiting the US-led battle against Islamic State militants to strike at Kurdish forces in Iraq and Syria that it sees as a threat to Turkish rule.
The airstrikes were prompted by intelligence indicating a likely Islamic State attack. The US said a deal has been reached with Turkey to use a key airbase.