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.

Azerbaijan Airlines plane crash, likely caused by Russian air defense, shines light on a glaring issue the Kremlin has long swept under the rug.

Russian President Vladimir Putin apologized for the plane crash in Russian air space on Christmas Day that left 38 people dead in a statement that said Russia was targeting Ukrainian drones over the plane’s planned destination at the time, but stopped short of taking responsibility.