You are correct that jus in bello and jus ad bellum must be distinguished. I could have pointed that out more clearly in my post.

I intended to discuss only the legality of Russia’s resort to use of force against Georgia. Where our analysis leaves the issue of proportionality of use of force under jus ad bellum and enters the issue of armed forces’ conduct under jus in bello is a matter of debate. I would argue that it is not at all obvious that what Russian forces are doing right now is separate from Russia’s original use of force against Georgia.

Your point seems to be, however, that even the original use of force was illegal because self-defence is legal only when the state’s own territory is attacked. Do I understand you correctly? Does it mean that if Russian forces stationed in South Ossetia under an agreement with Georgia are attacked, Russia’s use of force is always illegal? Can you cite an authority for that?

I read with interest your post, since I was to some extent invited to do so. I’d like to point out from the beginning that in your discussion you seem to blur the distinction between jus ad (contra) bellum and jus in bello. For the ones who are not so fond of Latin the first term relates to law on the use of force and the second term on the law of armed conflict. While the first is regulated under the UN Charter, the second part of the law of war is codified under the 1949 Geneva Conventions and the 1977 Additional Protocols. Whether resort to use of force is legal or not, once a conflict starts the parties are bound by the law of armed conflict and should abide by it.
Contrary to what you say what happened before the 8th of August is certainly relevant to assessing the escalation of the conflict into a full-fledged war.
South Ossetia is not Russian territory, so it is difficult to see how self-defence comes into play? Unless the self for Russia includes South Ossetia and Abkhazia. Until some days ago it did not. Is it that out of a sudden the notion of ‘territorial integrity’ has no value whatsoever for Russia?
Russian attacks are clearly disproportionate and the Russian troops have certainly gone far beyond what was necessary to protect their peacekeepers and South Ossetians of Russian citizenship. Taking and holding the city of Gori and other Georgian cities under the pretext of maintaining security or removing a threat (?) is simply an excess of the use of force. Continuing military operations deep into Georgian territory and fortifying their positions days after a cease-fire and withdrawal of troops has been signed is a clear violation of international law.
But as they say ‘there is nothing new under the sun’.

What is said here is not the full story. It does not cover the parts where South Ossetia was using artillery on Georgain villages or evacuation people before the conflict. Hence what he say here is worthless in my opinion.

Georgia is to blame for all of this. Let’s not forget that.

Russia should probably not have crossed the Ossetian border into Georgia, but it was perfectly justified in using force to repel an invasion.

Considering Russia’s history, military strength, and image in the Western world as something of a war-monger, we have to appreciate that Russia’s response to Georgian aggression has been remarkably restrained.

Although lacking in international recognition such a “de facto” state nevertheless has a legal standing under international law. For instance, it is not free to violate jus cogens just as Georgia is also not free to do so. This is a 3 way street: Georgia can not use force against its own citizens unless in self defense, it can not do so against a recognized neighbor, and it can not do so against an unrecognized de-facto state neighbor. Not even to enforce a territorial claim.