Well, war crimes is a bit different because we're talking about a nation's treatment of non-citizens (like prisoners of war). What the Nazis did to the Jews wouldn't really be war crimes because there was no Jewish nation for Germany to be at war with. This was a group of German citizens (except in those countries that Germany invaded, then the issue of war crimes comes into play). But even with the issue of war crimes, are nations really accountable to other nations?

__________________
A panda walks into a cafe. He orders a sandwich, eats it, then draws a gun and fires two shots in the air.

"Why?" asks the confused waiter, as the panda makes toward the exit. The panda produces a badly punctuated wildlife manual and tosses it over his shoulder.

"I'm a panda," he says at the door. "Look it up."

The waiter turns to the relevant entry and, sure enough, finds an explanation.

"Panda. Large black-and-white bear-like mammal, native to China. Eats, shoots and leaves."