Destabilizing Syria for fun and profit

Turkey just shot down a Russian airplane that was en route to a bombing missing against ISIS.

Map analysis shows the plane was over Turkish airspace for less than 2 miles, an eye blink in jet speed time.

There’s also ample evidence that Turkey has been involved in training ISIS and cooperating with arms smuggling on their behalf.

Their goal: Destabilize their neighbor Syria.

What does it mean when a NATO member is engaged in this kind of activity?