Turkey's prime minister, responding to the downing of a Turkish jet by Syrian forces, said Tuesday that Turkish military will respond to any future violation of its border by Syrian military elements.

"The rules of engagement of the Turkish Armed Forces have changed," Recep Tayyip Erdogan said. "Any military element that approaches the Turkish border from Syria by posing a security risk and danger will be regarded as a threat and treated as a military target."

Syria insists that the Turkish plane violated its air space on Friday. But Turkey says that although the unarmed RF-4E reconnaissance jet had unintentionally strayed into Syria's air space, it was inside international airspace when it was brought down.

The head of the NATO military alliance called the downing of the jet unacceptable on Tuesday, shortly after Turkey briefed NATO's North Atlantic Council in discussions held under Article 4 of NATO's founding treaty, which allows a NATO member to request consultations if its security has been threatened.