RUSSIA'S SYRIA INTERVENTION WAS ALREADY UNPOPULAR AT HOME. IT COULD BECOME MORE SO NOW.

In terms of Syria, then, those flights may be about Russia finding a way to assert its military presence, and preempt any Western effort to chase it off, by taking pushy and provocative steps like buzzing Turkish airspace.

That this was risky and dangerous may have been precisely the point: With its flights across NATO airspace in the Baltics, Russia was likely seeking to raise the stakes and hope that Western countries, wanting to avoid an incident like today's shoot-down, would take on the burden of deescalating. But that is not how things worked out with Turkey.