What counts in the first instance is the perspective of the ruling groups, and, more importantly now, the inter-relationships of those groups. I think the title of Ellen Wood's book is in itself enormously illuminating: The Empire of Capital. That capital exists globally, but needs to be 'enforced' within each state. (I assume a global state is a chimera.) And _certain_ nations assume the role of policing 'rogue' states: that is, states that are failing in their responsibility to keep their nation safe for business. Much to the satisfaction of the EU, Japan, Russia, and China (whatever their rhetoric may be at times) the U.S. is playing the role of World Cop. That is _different_ from U.S. imperialism; in fact I am beginning to feel that the term imperialism is losing its usefulness.
Neither China nor the EU nor any other core military power is going to prosecute any u.s. war criminal - and it is just as absurd to envision the u.s. prosecuting a French war criminal. (It was France, after all, that was primarily responsible for the Rwanda, but only local villains were (or ever will be) punished.
The punishment of War Criminals remains, unambiguously, a form of Victor's Justice, and as such is to be opposed.
Carrol