While I am not going to respond about the war in Georgia, because I know too little about it to have an actual opinion, I must say Highwind Dragoon is making a good point. It's not like any national group who live in a certain territory, and wish to have a local government rather than obey state law can just declare independence. If they could, there would be no law and that would be anarchy.
If there is any set of rules, which I see as the ultimate basis for modern democratic law, it's the United States Declaration of Independence.
A magnificent document, which was written to justify the right of the American colony to become independent from the British Empire.
USA is an example for a country who did not have a national identity (as it was formed from different nations), and achieved its independence mostly out of political and economic reasons. And so it states:
When in the Course of human events, it becomes necessary for one people to dissolve the political bands which have connected them with another, and to assume among the powers of the earth, the separate and equal station to which the Laws of Nature and of Nature's God entitle them, a decent respect to the opinions of mankind requires that they should declare the causes which impel them to the separation.
Of course, England was not willing to let America slip out of their hands, and so a war followed.
This is what usually happens when a certain group tries to form an autonomy against the will of the state controlling it- the state uses military power in order to make it submit to its will; a lot like a slave demanding his freedom from his master, the master would certainly not let him get away. He would shoot him, or punish him.
Sometimes the military power is used rightfully, and sometimes not. But that can be argued.