President Vladimir Putin on December 28 apologized to Azerbaijan's President Ilham Aliyev for what the Kremlin called a "tragic incident" over Russia in which an Azerbaijan Airlines plane crashed after Russian air defenses were fired against Ukrainian drones.

Putin called President Ilham Aliyev and "apologized for the tragic incident that occurred in Russian airspace and once again expressed his deep and sincere condolences to the families of the victims and wished a speedy recovery to the injured," the Kremlin said.

"At that time, Grozny, Mozdok and Vladikavkaz were being attacked by Ukrainian unmanned aerial vehicles, and Russian air defense systems repelled these attacks."

The Kremlin said civilian and military specialists were being questioned.

Putin also phoned Kassym-Jomart Tokayev, his counterpart in Kazakhstan, to express his condolences over the loss of life in the crash, the Kremlin said.

Meanwhile, Reuters says the extremely rare publicized apology from Putin was the closest Moscow had come to accepting some blame for December 25 disaster, although the Kremlin statement did not say Russia had shot down the plane, only noting that a criminal case had been opened.

Four sources with knowledge of the preliminary findings of Azerbaijan's investigation told Reuters on December 26 that Russian air defenses had mistakenly shot the airliner down.  Passengers said they heard a loud bang outside the plane.

Azerbaijan’s flight J2-8243, en route from Baku to the Chechen capital Grozny, crash-landed on December 25 near Aktau in Kazakhstan after diverting from southern Russia, where Ukrainian drones were reported to be attacking several cities.  At least 38 people were killed.