At Turkey's request, NATO ambassadors have met in Brussels to review the shooting down of a Turkish military jet fighter by Syrian air defences.
It is only the second time in NATO's 63-year history that it has met under Article 4 of its charter that provides for consultations when a member state feels threatened.
The BBC reports that in a letter to the UN Security Council, Turkey described the incident as a "hostile act by the Syrian authorities against Turkey's national security".
Turkey's deputy prime minister said it "would not go unpunished", but stressed it was not seeking military action.
Damascus insists the F-4 Phantom jet was shot down inside Syrian airspace.
