Originally Posted by CyberSEO

Nobody knows and nobody cares, because the investigation was not performed by Russia. Russia has no access to all those materials. So the officials here may have their own versions/guesses but nothing else. The Ukrainian territory was not controlled by Russia and the aircraft was not guided by the Russian operators - it haven't reached Russian territory, so as the Ukraine - they were 100% responsible for that flight till it not crossed entered the Russian air space.