Turkey's foreign ministry claims a Russian warplane strayed into Turkey's air space for a second time yesterday.
It follows a similar incident the day before, which Moscow insists was an accident.
Russian war planes are now regularly flying over the region, launching air strikes on Syria.
Turkish prime minister Ahmet Davutoglu says it won't be frightened.
"Whoever it is, wherever it comes from, whatever direction it comes from, our rules of engagement are clear when our airspace is violated.
"First we warn, we warn in a friendly way whatever country it may be."
The US government says it does not accept an incursion by a Russian jet into Turkish airspace was an accident.
Moscow says it was in Turkish territory "for a few seconds".
Meanwhile NATO's demanded Russia concentrate on Islamic State targets inside Syria, ordering it to stop hitting civilians.