United Nations - The Turkish government sought Monday to galvanize support in NATO and at the United Nations for a tough response to Syria's downing of a Turkish fighter jet, but it left its partners confident that it is not preparing a military response.

With tensions rising over the Syrian government's 15-month-old crackdown on opposition groups, Turkey appeared to be pursuing a carefully calibrated strategy aimed at securing an unambiguous international condemnation of Syria while ensuring that the incident doesn't spiral into a shooting war between the neighbors.

"We would like to see more pressure from our allies, particularly more leadership from the United States," said a senior Turkish official, who spoke on the condition of anonymity to discuss diplomatic and military issues. "That's what we are trying to mobilize."

Concerns that Turkey might respond militarily were heightened when its government disclosed Monday that Syrian forces had fired briefly at a second Turkish aircraft as it searched for the downed pilots of the first plane Friday. Relations between the two neighbors have deteriorated sharply in recent months.

Turkey has become a haven for Syrian refugees and for defectors from the Syrian military. Turkish news outlets reported Monday that a fresh wave of defectors had recently crossed the border, including a general, two colonels and at least 33 soldiers. But officers with the rebel Free Syrian Army, which is based in southern Turkey, said the defections were not new. Such announcements are often delayed so defectors can ensure their families are safe.

As NATO members prepared to meet today to discuss the Friday attack on the Turkish fighter jet off the Syrian coast, the United States and other allies denounced the incident.

Meeting in Luxembourg on Monday, European Union foreign ministers condemned the "unacceptable shooting down by Syria of a Turkish military plane" and praised the Turkish government for its "measured and responsible initial reaction." The E.U. imposed new sanctions aimed at Syrian banking, military and state media entities, according to British Foreign Secretary William Hague, and will strengthen the arms embargo to explicitly prohibit the insurance of arms shipments.

White House spokesman Jay Carney said, "We will work with Turkey and other partners to hold the (Syrian) regime accountable."

The United States and its European partners appeared keen to avoid being drawn into a military confrontation with Syria. "What happened is to be considered very seriously," said Dutch Foreign Minister Uri Rosenthal. But he added, "We do not go for any interventions."

Turkey and Syria offered sharply conflicting accounts of what occurred, with Ankara insisting that the plane was shot down in international airspace, 13 nautical miles from the Syrian coast, after it inadvertently crossed briefly into Syrian airspace while on a routine mission to test Turkish radar systems.

Syrian Foreign Ministry spokesman, Jihad Makdissi, said the Turkish jet was flying low and fast in Syrian airspace, about one mile from the coast, when it was downed by gunners, who didn't realize it was Turkish.

"Syria reacted to the breach," Makdissi said at a news conference in Damascus. "We had to react immediately. Even if the plane was Syrian, we would have shot it down."

He also cautioned against NATO involvement in Syria. "I want to reassure everyone that the Syrian territories, waters and airspace are sacrosanct for the Syrian army," he said.

Turkey called Tuesday's NATO meeting in Brussels under Article 4 of the NATO charter, which allows consultations in case of a threat. It is not considered as serious a step as Article 5, which requires members to help defend any ally that is under attack.

A NATO official, speaking on the customary condition of anonymity, noted that the organization's secretary general has repeatedly stated that "NATO has no plans to intervene whatsoever in Syria, and that has not changed."

The senior Turkish official said his government would offer NATO ambassadors on Tuesday a detailed description of the downing of the plane. The Turks are not expected to ask for military retaliation. Rather, he said, they want Syria to understand that Turkey and its NATO allies will meet any future incident with force. "We need to see that this organization is solid in support of our position and that if something serious happens they will be solidly behind us," he said.

At the same time, he said, the Turkish delegation at the United Nations is citing the incident as evidence of the need for tougher Security Council resolutions against Syria.

Diplomatic efforts to rein in the violence in Syria, which has killed more than 10,000 people, have stalled in recent weeks.