The North Atlantic Council met for consultations on Tuesday on a request from Turkey following the downing of one of its fighter jets by Syria, NATO diplomats said.
The meeting began shortly after 0800 GMT, gathering ambassadors of the 28-nation Atlantic alliance and was chaired by NATO secretary-general Anders Fogh Rasmussen, who is due to hold a news conference at around 0930 GMT.
Turkey requested consultations under Article 4 of NATO's founding treaty, enabling any of the allies to call for talks should they consider their territorial integrity, political independence or security under threat.
It is only the second time since the North Atlantic Treaty Organization was set up in 1949 that consultations have been requested under Article 4, the last time in 2003 also being on a request from Turkey during the Iraqi war.
No decisions are expected after the talks during which Turkey will outline to allies the circumstances of the downing of its Phantom 4 fighter on Friday, a diplomatic source said.