NATO Secretary-General Anders Fogh Rasmussen has vowed that NATO will "stand together with Turkey in the spirit of strong solidarity" amid heightened tensions with Syria following the downing of a Turkish jet last week.
Rasmussen said that the security of the alliance was "indivisible" but that NATO diplomats who met in Brussels on June 26 did not discuss whether to invoke Article 5 of NATO's charter, which would categorize the downing of the jet as an attack on the entire alliance.
"We consider these acts to be unacceptable and condemn it in the strongest terms," Rasmussen said. "It is another example of the Syrian authorities' disregard for international norms, peace and security, and human life."
Ankara said earlier it would ask its NATO allies to invoke Article 5 to help secure Turkey's border against threats from Syria.
Rasmussen would not discuss details presented by Turkish diplomats to the North Atlantic Council, which includes ambassadors of the 28 NATO countries.
Turkish Prime Minister Recep Tayyip Erdogan told parliament on June 26 that the Turkish military will respond to any future violations of its border by military units from Syria.
"After this latest incident, we have now passed to a new state," he said. "We will never tolerate, nor will we let go unpunished, any security threat created by the Syrian regime on our borders."
Erdogan said Syrian helicopters had violated Turkish airspace five times recently and that Turkey had not responded. But he said that Turkey will from now on "respond to all violations on the Syrian border," warning the Syrian regime "not to make the mistake of testing" Turkey's "determination" and capacity to respond.
Syrian Foreign Ministry spokesman Jihad Makdissi called the Turkish jet in "clear breach of Syrian sovereignty."
"The rules of engagement of the Turkish armed forces have changed in accordance with this new state," Erdogan said. "Any military element approaching Turkey from the Syrian border and representing a security risk and danger will be assessed as a military threat and will be treated as a military target."
In a letter to the UN Security Council, Turkey rejected Syrian allegations that the Turkish jet violated Syrian sovereignty, describing the incident as a "hostile act" by Syria and a "serious threat to peace and security."
Turkey's Deputy Prime Minister Bulent Arinc said for the first time that Syrian forces had opened ground fire on a Turkish search-and-rescue plane shortly after the downing of the reconnaissance jet, but did not say if the search-and-rescue plane was hit.
NATO Secretary-General Anders Fogh Rasmussen briefs the media after a meeting of the North Atlantic Council in Brussels on June 26.
"Our Foreign Ministry and chief of staff contacted Syrian authorities after this event and the fire was stopped," Arinc said.
The unarmed RF-4E reconnaissance jet was shot down 1.6 kilometers inside international airspace. Two Turkish pilots are still missing. Ankara says the plane was not spying on Syria.
Syrian officials have said that the Turkish plane violated Syrian airspace and the Syrian military was right to shoot the plane down. Damascus said the plane was hit by a short-range antiaircraft gun to prove that the plane was inside Syrian territory.
Arinc, however, said Turkey believed the plane was hit with a laser-guided or heat-guided missile capable of hitting the plane in international airspace.
"The data that we got shows that the plane was shot down by a heat-seeking or laser-guided surface-to-air missile," Arinc said. "As our plane's early warning system did not respond, we do not think that it was a radar-guided missile. Naturally, we can call this as an hostile act as our plane was targeted without any warning."
The Turkish deputy prime minister admitted the jet mistakenly strayed into Syrian airspace but said it left after warnings from Turkish radar operators.
He also said that the plane received no warning from Syrian forces during its five-minute flight inside Syrian territory.
"There is no doubt that Syrians deliberately targeted our plane in international airspace," Arinc said. "It was an extremely hostile action."
Reports from the Turkish-Syrian border say Syrian government troops in recent days have shelled Syrian refugees who have slipped across into Turkish territory.
WATCH: Amateur video apparently shot on June 26 shows gunfire and explosions in Qudsiya, a suburb of the Syrian capital, Damascus.
With reporting by Reuters, AP, and AFP