The regime of Syrian President Bashar al-Assad poses a threat to Turkey and its citizens, Turkish Prime Minister Recep Tayyip Erdogan said, the TRT Haber TV channel reported.
"After Syria shot down our Turkish military aircraft in international airspace, we will take more serious steps in the framework of international legal standards," Erdogan said.
The Turkish reconnaissance aircraft RF-4E which took off on Friday from an Erhach airbase in Malatya province in south-eastern Turkey, disappeared from the radar screens at about noon local time in the Mediterranean Sea to the south-east of the province of Hatay bordering on Syria.
Syria said it shot down a Turkish aircraft over its territorial waters after its invasion of Syria's airspace. However, Turkish Foreign Minister Ahmet Davutoglu said that the plane was shot down in international airspace and that wreckage fell into the territorial waters of Syria.