On the other hand Armenian army is standing alone against this deadly alliance, although russian support is with Armenia along with France and some other European countries.Now the main problem is Turkey, because it is the same country who is responsible for provoking the Azerbaijan and supplying weapons and fighters to fight for Azerbaijan.This Turkey is also member of NATO. Now russia has a pact signed with Armenia also,so any attack on Armenia will be considered as attack on Russia and then russia will have to enter the war. But right now war is limited to Nargono karabakh which is a conflicted zone,so russia can't enter till the attack on mainland of Armenia.
Also one major reason for russia for not entering the war is Turkey's NATO membership. So a attack on Turkey will be considered as attack on NATO,and then America and europian countries which are NATO members will have to fight against russia also. So Turkey has played the cards very well,by supporting Ajarbaijan they are projecting themselves as a role model for muslim countries,at the same time withholding russia to enter the war,and compelling America to stay away as well.Overall situation is very serious and no-one know when the restricted conflict will engage other countries of this world also,and this can be a reason for world war 3.