The Russian Defense Ministry has confirmed that an Su-25 close-support military aircraft was shot down over Syria on February 3 and the pilot was killed.
A ministry statement said the pilot ejected from the aircraft but was killed while resisting capture by rebels fighting against the Syrian government. The statement said preliminary evidence indicates the plane was shot down by a shoulder-launched antiaircraft missile.
The London-based Syrian Observatory for Human Rights said earlier that rebel forces had shot down an Su-25 in Idlib Province in northwestern Syria.
A jihadist group called Hayat Tahrir al-Sham claimed responsibility for the downing, saying a shoulder-launched missile had been used. The statement on the rebel-affiliated media channel Ibaa did not mention the Russian pilot.
Russian military correspondent Aleksandr Kots posted on social media a video purportedly showing rebel fighters picking over the burning wreckage of an Su-25.
The Russia-based, independent Conflict Intelligence Team posted photographs they say showed the dead body of the pilot and a paper recommending a man named Major Roman Fillipov for a state award that was allegedly filled out by Russian air group commander Lieutenant Colonel Sergei Aksyonov.
Novaya Gazeta quoted an unidentified Defense Ministry source as confirming that the pilot was Filippov. According to the newspaper, he was a Ukrainian pilot from Crimea, the Ukrainian region that Russia annexed in 2014.
Federation Council member Frants Klintsevich, chairman of the Defense and Security Committee, said an investigation would be launched into the circumstances of the downing.
"As I have said before," Klintsevich told Interfax, "I am positive that the militants have [shoulder-launched antiaircraft weapons], and they have been supplied by the Americans via third countries."
Vladimir Shamanov, chairman of the State Duma's Defense Committee, said "there are over 1,000 U.S. instructors in Idlib, so it could be a provocation."
The U.S. State Department said it was "deeply concerned" at reports of shoulder-launched antiaircraft systems being used and denied the United States had ever supplied such weapons.
"The United States has never provided MANPAD missiles to any group in Syria, and we are deeply concerned that such weapons are being used," spokeswoman Heather Nauert said.
"The solution to the violence is a return to the Geneva process as soon as possible and we call on Russia to live up to its commitments in that regards," she added.
Russia has been conducting military operations in support of Syrian President Bashar al-Assad since September 2015.
The February 3 incident was the first time Syrian rebels have shot down a Russian warplane. In July 2016, rebels used a shoulder-launched missile to shoot down a Russian-made Syrian helicopter manned by a Russian crew.
In all, Russia has reported losing four jets and four helicopters during the Syrian campaign, including two jets that crashed while trying to land on the Admiral Kuznetsov aircraft carrier and an Su-24 bomber that was shot down by Turkey in November 2015.
The Su-25 is a single-seat, twin-engine jet designed to provide close air support for troops on the ground.