"Any number of groups could have wanted Russian ambassador dead..." http://www.cnbc.com/2016/12/19/who-...or-to-turkey-it-could-be-a-lot-of-people.html If memory serves me correctly, a single murder was essentially the spark that lead to WW1. Turkey and Russia aren't exactly friends, and the gunman was a Turkish policeman. This on top of Turkey shooting down a Russian fighter within the last couple years can't be good for relations. Additionally, I don't believe that Russia and Turkey have the same interests in Syria. If I'm not mistaken, Turkey is still a member of NATO. It probably won't amount to anything, as the article indicates, but still could become very interesting.
Let's not forget that Russia has been accused of tempering with US elections. For those who would believe so, I'd find it difficult that there would be no consequences for Russia.