In times of war and conflict, accidents happen, sometimes with devastating consequences. Last October a Sukhoi fighter jet - again, an Su-34 - crashed in the Russian city of Yeysk killing at least 13 people.
The military says it has launched an investigation into the incident. Quoting a former military pilot, pro-government news site Moskovsky Komsomolets suggested "the conclusions [of the investigation] are unlikely to be made public, but lessons will be learned".