1. After Nuremburg it was a show trial put on by Stalin, there was no justification for the court -- it wasn't like the laws they broke existed in some sort of international context. 2. Not to defend Guantanamo -- I think it's abhorrent, but it is not a war crimes court, it's a place where prisoners of "war" are being taken.

As I said before, I think the entire concept of war crimes in nebulous and if there is any enforcement it should be done by country affected.