The Russians:
A) were annoyed by the expansion of Nato and the EU;
B) were annoyed by Kosovo's independence and thought what the heck, we will 'liberate' South-Ossetia; and
C)were annoyed by Saakashvili's provocations who thought that the US were going to help him. Quod non!
...therefore genocide and pillaging are a perfectly justified response!
Russians are, as a culture, super-paranoid. They would probably find the need to go blow up a village of 10 people & a goat because that village was a threat to Russia.