MOSCOW (AP) — Russian President Vladimir Putin on Saturday apologized to his Azerbaijani counterpart for what he called a “tragic incident” following the crash of an Azerbaijani airliner in Kazakhstan that killed 38 people, but stopped short of acknowledging that Moscow was responsible.

Putin’s apology came as allegations mounted that the plane had been shot down by Russian air defenses attempting to deflect a Ukrainian drone strike near Grozny, the regional capital of the Russian republic of Chechnya.