Even as a probe was starting of the crash of an Azerbaijan Airlines airliner in Kazakhstan, speculation was mounting about why the plane went down.

Mobile phone footage circulating online appeared to show the Azerbaijani Airlines plane making a steep descent before slamming into the ground in a fireball in western Kazakhstan.

According to Euronews sources, the crash of the Azerbaijan Airlines plane flying from Baku to Grozny on 25 December was caused by a Russian surface-to-air missile that exploded nearby. Source: Euronews Quote: "Sources in the Azerbaijani government confirmed in an exclusive statement to Euronews on Thursday that a Russian surface-to-air missile was the cause of the crash of an Azerbaijani Airlines plane in Aktau on Wednesday.