Russian President Vladimir Putin said Saturday that Russia’s air defense systems were active when an Azerbaijan Airlines flight attempted to land in Grozny, Chechnya on Wednesday.

Putin apologized for the “tragic incident” in Russian airspace, but the Kremlin did not take responsibility for downing the Azerbaijan Airlines flight.

On 25 December, 38 people died when an Azerbaijan Airlines flight, which had been due to land in Russia, crash-landed in Kazakhstan. The circumstances around the crash remain unclear, but limited evidence so far suggests it may have been damaged by missiles fired by a Russian air-defence system as it tried to land in Chechnya.