NATO's ruling council has held urgent talks on the Syria crisis after at least 33 Turkish soldiers were killed in an air strike blamed on Damascus.
Ambassadors of all 29 member states within the military alliance were brought together at the request of Turkey, which claims to have retaliated by attacking Syrian government targets.
Threats to Turkish "territorial integrity, political independence or security", stipulated under Article 4 of NATO's founding Washington Treaty, were at the centre of the consultation.
Last night's strike hit Syria's northwestern Idlib province, where President Bashar al-Assad is seeking to wipe out the last rebel stronghold in the area.
A total of 54 Turkish security personnel have been killed in the province this month.
The number of personnel killed in the latest attack stands at 33, though dozens were also injured.
Turkish Communications Director, Fahrettin Altun, says that a systematic genocide has unfolded before public eyes, after months of air bombardments.
We have been targeting all regime positions from the ground and the air. We call on the parties of the Astana Process and the broader international community to honor their responsibilities. A repeat of past genocides such as those in Rwanda and Bosnia cannot be allowed in Idlib.— Fahrettin Altun (@fahrettinaltun) February 28, 2020
Russia, a key military ally to Syria, is understood to have have been behind many of the attacks. Meanwhile, Turkey backs the rebels fighting Syrian forces.
Mr Altun wrote on Twitter: "We have been targeting all regime positions from the ground and the air."
Moscow claims the Turkish soldiers killed were operating alongside jihadist fighters at the time of the strikes and denies its own air force was involved.
NATO Secretary General Jens Stoltenberg has condemned "indiscriminate" attacks, during a phone conversation with Turkish Foreign Minister Mevlut Cavusoglu.
Ankara called talks under Article 4 twice in 2012, after one of its jets was shot down by Syrian forces, prompting the alliance to deploy Patriot missile batteries in Turkey as a defensive measure.
In response to the crisis, the US has stood by its Turkish NATO ally, a spokesperson calling for "an immediate end to this despicable offensive by the Assad regime, Russia and Iranian-backed forces."
Meanwhile, UN Secretary General Antonio Guterres called for an immediate ceasefire in the Middle Eastern country.
The European Union warned that the fighting in northern Syria could lead to open war and that the 27-nation bloc stands ready to protect its security interests.
Apart from providing some aerial surveillance, NATO plays no direct role in Syria, though its members are divided over Turkey's actions there.
Many European nations are concerned a new wave of migrants who fled from Syria to Turkey could make their way elsewhere, causing a separate crisis.
Turkey hosts some 3.6 million Syrians and under a 2016 deal with the European Union, but President Erdogan has threatened to allow them to travel elsewhere in Europe.
A government official said Greece has beefed up border security "to the greatest possible degree… on land and at sea", as migrants lined the Turkish border in recent hours.