re: The Russians say the chemical attack was by the rebels, America says by Assad.

the problem is just how we view conflict compared to how they view conflict

like take America...our "war values" are still based in the Revolutionary War but most recently WWII. when we "win", we try to mold the losing side into our values system (although the post-WWII division of Europe was pretty terrible, but we couldn't really do anything). we don't have this irrational belief against the common people who were our prior enemies

the Middle East (as well as other areas, like Sub-Saharan Africa and Southeast Asia) has been at war for so long with so many cultural and ethnic conflicts/oppression that they are just harder people. when one side "wins", they think of this as an opportunity to slaughter their prior enemies, regardless of the individual participation in the actual conflict. they still see victory in war as requiring of spoils and a license to exert dominion over the losing side

so like your average American thinks of this conflict and goes "well we just need a non-dictator to win and with US support, they'll develop institutions and create a better society for all" but in reality it's more "they will consolidate power and develop institutions and stability so that they can more easily exterminate all opposition and exact revenge for previous oppression"