President Obama blames the incident on Russia being in Syria

"I do think this points to an ongoing problem with Russian operations [in Syria] ... in the sense that they are operating very close to a Turkish border and they are going after moderate opposition.

"If Russia is directing its energies towards Daesh and ISIL, some of those conflicts or potentials for mistakes or escalation are less likely to occur.…

Al Jazzera
World leaders react to Turkey's downing of Russian jet