Here's the region known as "The Caucasus"
The North Caucasus include Chechnya
Chechnya, which is part of Russia, has seen violent conflict between the Russian government and the Chechen separatist movement
Syria and The Caucasus are pretty close to one another
The conditions in Chechnya have given rise to extremism and terrorism
For Russia, the threat of terrorism is real and persistent
So, imagine you're Russia.
This incredibly helpful analysis comes from Matthew Rojansky of the Kennan Institute.