ANKARA, Turkey – NATO will hold emergency talks Tuesday to discuss Syria’s downing of a Turkish jet fighter, but the alliance is not expected to take military action, even if it confirms Turkey’s claim that the unarmed plane was attacked in international airspace.

The incident has further raised regional tensions over the conflict in Syria, where some 40 people were reported killed Sunday in new clashes between rebels and government troops.

On Sunday, Secretary of State Hillary Clinton sharply criticized Syria for downing the Turkish plane, an action that Turkey’s Foreign Ministry called an “open and grave violation of international law” that would justify retaliation.

“The United States condemns this brazen and unacceptable act in the strongest possible terms,” Clinton said in Washington. “It is yet another reflection of the Syrian authorities’ callous disregard for international norms, human life, and peace and security.”

Clinton said Washington will maintain close contact with Turkish officials as they determine their response, including via the U.N. Security Council. “We will work with Turkey and other partners to hold the Assad regime accountable,” she said.

Turkish state media reported Sunday that the RF-4E reconnaissance plane’s wreckage was found in the Mediterranean Sea at a depth of 4,265 feet, but officials did not confirm the report. The two pilots remained missing.

Turkish Foreign Minister Ahmet Davutoglu said the jet was on a training flight to test Turkey’s radar capabilities, not spying on Syria. He said the plane mistakenly strayed into Syrian airspace Friday, but was quickly warned to leave by Turkish authorities and was a mile inside international airspace when it was shot down.

Syria insisted Saturday that the shooting was “not an attack” and that the aircraft had violated its airspace. But Turkish authorities say Syria didn’t warn the Turkish plane or send its own jets to confront it.

At the request of Turkey, NATO’s governing body will meet Tuesday to discuss the incident, said Oana Lungescu, a NATO spokeswoman. The consultations were called under article 4 of NATO’s founding Washington Treaty.

“Under article 4, any ally can request consultations whenever, in the opinion of any of them, their territorial integrity, political independence or security is threatened,” Lungescu said. The North Atlantic Council — the ambassadors of the 28 NATO countries — will decide whether to respond, she said.

The last time article 4 was invoked was nine years ago — also by Turkey — after tensions with neighboring Iraq escalated. However, that case did not lead to the invocation of article 5, which declares that an attack against any single NATO country shall be considered as an attack against them all.

“No one should dare to test Turkey’s capabilities,” Davutoglu said Sunday.

Turkish Prime Minister Recep Tayyip Erdogan was expected to make a statement Tuesday and might announce some retaliatory steps.

Syrian Foreign Ministry spokesman Jihad Makdissi told Turkish TV news channel A Haber by phone that the downing was “not an attack.”

“An unidentified object entered our airspace and unfortunately as a result it was brought down. It was understood only later that it was a Turkish plane,” A Haber quoted Makdissi as saying Saturday. “There was no hostile act against Turkey whatsoever. It was just an act of defense for our sovereignty.”

Despite some opposition leaders’ calls for Western military intervention in Syria, the United States and allies have been hesitant to get involved in what could prove a protracted conflict, preferring the diplomatic route. Syrian allies Russia and China have shielded Syria from U.N. sanctions and stridently oppose any military intervention.