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.

U.S. officials say Russia could be behind a passenger plane crash in Kazakhstan that left dozens dead on Christmas Day. U.S. officials say it looks like the plane was hit by a Russian air defense system,

As authorities in several countries tried to determine what caused the deadly crash of a passenger airplane in Kazakhstan, investigators and experts Thursday were focusing on the possibility that a Russian air defense system had struck the plane.