Turkey recently launched Operation Claw-Sword against Kurdish separatists that they say are responsible for the Istanbul bombing on 13 November. It is a solo operation however. Why doesn't Turkey trigger NATO's collective defense article to get the rest of NATO to join the operation? After all, the September 11 attacks demonstrated that terrorist activity counts for NATO article 5.
Turkey has apparently threatened to trigger the clause twice a decade ago, but doesn't seem to have done it for this attack.