After an Azerbaijan Airlines jet crashed in Kazakhstan, speculation mounted about why the plane went down and whether possible Russian air defense action may have played a role.

An Azerbaijan Airlines Embraer 190 was en route from Azerbaijan's capital of Baku to the Russian city of Grozny when it crashed, killing 38 people onboard.

Russian aviation authorities said the Azerbaijan Airlines plane had hit a flock of birds. But some experts cast doubt on that account, pointing to footage showing apparent holes in the fuselage.