But in the United Nations Charter, there are two grounds for war. One is self-defense. The other is a UNSC resolution designating a state as a source of disorder in the international system.
By firing on the Turkish plane (more especially in international waters), Syria has presented Turkey with a legitimate casus belli, a legal cause for war. The news that Syria actually tried to shoot down a second Turkish plane underscores this legal point. Turkey may defend itself. ...[The plane was shot down over international waters; it may have veered into Syrian airspace at one point, but that would have merited a warning, not a shoot-down.]
Here is the kicker. Turkey is a member of the North Atlantic Treaty Organization. And the NATO charter’s article 5 declares that an attack on one member is an attack on all. NATO is duty-bound to defend Turkey if it is attacked and if it asks for help. Article 4 allows a country to call for consultations among the allies if it feels its territorial integrity is threatened.
Turkey is asking for help. It is asking that NATO be convened under Article 5 for only the second time in the organization’s history.
Turkish intelligence says that it has evidence that the Syrian military knew that the plane was Turkish, referring to it as “komsu,” the Turkish word for “neighbor.”
...Turkey and Syria had established good relations in the last decade, but the revolution and civil war have forced Turkey to take a stand. Ankara has sided with the revolutionaries, and called for Syrian President Bashar al-Assad to step down. Qatar and Saudi Arabia are suspected of supplying the Syrian revolutionaries with rocket-propelled grenades and other war materiel that would allow them to take on the powerful Syrian military machine. Some observers believe that the RPGs and other weapons are being smuggled in from Turkey. And, such smuggling operations might need aerial support to make sure there aren’t Syrian troops along the smuggling route.
So the Syrians may have deliberately been sending Turkey a message, to back off.
It was a stupid move. As long a Syria did not engage in hostilities with other states in the region, it was teflon, since Russia and China were protecting it at the UN. But now that it has fired on a NATO plane, it has offered Turkey and its colleagues a legal way to use force.
Via Spencer Haskins