ANKARA, Turkey — Turkey shot down a Russian fighter plane it said had crossed into its territory from Syria on Tuesday, killing at least one of the two pilots and marking the first time in half a century that a NATO member has downed a Russian plane.
The long-feared incident highlighted the growing complexity of Syria's civil war, as multiple groups with clashing alliances fight on the ground and the sky is crowded with aircraft bombing various targets. It immediately prompted fierce reaction from Moscow.
Russian President Vladimir Putin called Turkey's action a "stab in the back by the terrorists' accomplices" and warned of "significant consequences," while Russian Foreign Minister Sergey Lavrov cancelled a trip to Turkey which had been planned for Wednesday.
NATO Secretary-General Jens Stoltenberg called on all parties to be prudent and to contribute to reducing tensions.
"As we have repeatedly made clear we stand in solidarity with Turkey and support the territorial integrity of our NATO ally, Turkey," Stoltenberg told a news conference after an extraordinary meeting of the alliance's decision-making North Atlantic Council, called at Turkey's request.
He called for "calm and de-escalation, and renewed contacts between Moscow and Ankara.
Turkey said two SU-24 planes ignored several warnings that they were nearing, and then intruding into, Turkish airspace. In a letter to the U.N. Security Council and Secretary-General Ban Ki-moon, obtained Tuesday by The Associated Press, it said the planes disregarded warnings and violated Turkish airspace "to a depth of 1.36 miles and 1.15 miles in length for 17 seconds" just after 9:24 a.m.
It said one of the planes then left Turkish airspace and the other one was fired at by Turkish F-16s "in accordance with the rules of engagement" and crashed on the Syrian side of the border.
Russia insisted the plane stayed over Syria, where it was supporting ground action by Syrian troops against rebels.
Rebel forces fired at the two parachuting pilots as they descended, and one died, said Jahed Ahmad, a spokesman for the 10th Coast Division rebel group. The fate of the second pilot was not immediately known.
Later Tuesday, Russia's military said that one of two of its helicopters that were searching for the jet's crew in Syria was shot down by rebel fire and one serviceman was killed. The rest of its crew were evacuated and taken back to the air base used by Russia in Syria.
A U.S. defense official in Washington confirmed the Russian plane entered Turkish airspace before Turkey shot it down. The official, who was not authorized to discuss details of U.S. knowledge about the incident and spoke on condition of anonymity, said the Russian plane flew across a 2-mile section of Turkish airspace, meaning it was in Turkish airspace only for a matter of seconds.
Turkey and Russia have long been at odds over the crisis in Syria, where Turkey has been seeking the ouster of President Basher Assad — an important Russian ally.
Turkey has also voiced concerned over Russia's bombing of Turkmen areas in Syria and the fact that the Russian operations have complicated the possibility of creating a safe zone in northern Syria to protect civilians as well as moderate rebels fighting Assad. The creation of a safe zone has been a long-term Turkish goal.
"We will never tolerate such atrocities as happened today and we hope that the international community will find the strength to join forces and fight this evil," Putin said.
Turkish Prime Minister Ahmet Davutoglu insisted his country has the right to take "all kinds of measures" against border violations, and called on the international community to work toward "extinguishing the fire that is burning in Syria."
But despite the harsh words, some analysts believe that Russia and Turkey have reasons not to let the incident escalate.
"Relations have been very strained between Russia and Turkey of late so Moscow will be trying its utmost to contain the damage this might cause," said Natasha Kuhrt, lecturer in International Peace and Security at King's College London.
"It's a serious incident in anybody's book," added Ian Kearns, director of the European Leadership Network, a London think-tank.
But Kearns said the Russian-Turkish economic relationship, including in the energy field, is important to Moscow. And Russia and the West appeared to be moving toward an understanding of their common strategic interest in eradicating the Islamic State group following the bombing of a Russian airliner over Sinai on Oct. 31 and the Nov. 13 attacks in Paris.
The Turkish Foreign Ministry briefed diplomats from the five U.N. Security Council member countries on the incident Tuesday. Separately, a Russian diplomat was also summoned for a meeting during which Turkey "conveyed its sensitivities" over border violations.
In Moscow, Russia's Defense Ministry summoned Turkey's military attache for an official protest.
A Turkish military statement said the Russian plane entered Turkish airspace over the town of Yayladagi, in Hatay province. Turkish officials released what they said was the radar image of the path the Russian plane took, showing it flying across a stretch of Turkish territory in the country's southern-most tip.
Col. Steve Warren, spokesman for the U.S. military in Baghdad, said the U.S. heard communication between Turkish and Russian pilots and could confirm that Turkish pilots issued 10 verbal warnings before the plane was shot down.
The Russian plane was supporting Syrian troops which have been on the offensive in an area controlled by several insurgent groups including al-Qaida's branch in Syria, the Nusra Front, and the 2nd Coastal Division and the 10th Coast Division that include local Turkmen fighters.
Syrian Turkmen are Syrian citizens of Turkish ethnicity who have lived in Syria since Ottoman times and have coexisted with Syrian Arabs for hundreds of years. They were among the first to take up arms against Syrian government forces, as Turkey lent its support to rebels seeking to topple Assad.
In late 2012, they united under the Syrian Turkmen Assembly, a coalition of Turkmen parties which represents Syrian Turkmens in the Western-backed Syrian National Coalition opposition group. The military wing of the assembly is called the Syrian Turkmen Brigades and aims to protect areas with Turkmens from government forces and the Islamic State group.
Turkey has vowed to support the Syrian Turkmen and President Recep Tayyip Erdogan on Tuesday criticized Russian actions in the Turkmen regions, saying there were no Islamic State group fighters in the area.
However, Erdogan insisted Turkey does not harbor "enmity" toward Russia or any other nation and said Turkish level-headedness had prevented even graver incidents at the border.
Turkey has complained repeatedly that Russian planes supporting Assad are straying across the border. On Friday, Turkey summoned the Russian ambassador demanding that Russia stop operations in the Turkmen region.
Last month, Turkish jets shot down an unidentified drone that it said had violated Turkey's airspace.
The country changed its rules of engagement a few years ago after Syria shot down a Turkish plane. According to the new rules, Turkey said it would consider all "elements" approaching from Syria an enemy threat and would act accordingly.
Following earlier accusations of Russian intrusion into Turkish airspace, the U.S. European Command on Nov. 6 deployed six U.S. Air Force F-15 fighters from their base in Britain to Incirlik Air Base in Turkey to help the NATO-member country secure its skies.
Other countries have also complained recently that Russian military aircraft have markedly increased flights close to their airspace since 2014, when relations between Russia and the West significantly deteriorated amid the Ukraine crisis.
NATO said there was a 50-percent increase in 2014 in the number of times its member nations intercepted military aircraft flying near its borders, but there was no immediate tally of how many of those incidents involved Russian aircraft.
This year, Canada, Denmark, Lithuania, Estonia and Britain have all reported interceptions of Russian aircraft, as has non-alliance-member Sweden. The United States in turn complained of Russian aircraft intercepting one of its reconnaissance planes.
Sarah Lain, an analyst at the Royal United Services Institute, said the last time she could remember a NATO member country —the United States — shooting down a Russian/Soviet plane was the 1950s. "But the Soviets appear to have shot down more U.S. planes amid the Cold War," she added.
Vasilyeva reported from Moscow. Jim Heintz in Moscow, Robert Burns in Washington, Bassem Mroue in Beirut, John-Thor Dahlburg in Brussels, and Edith M. Lederer at the United Nations contributed to this report.