So you're saying that anything done by the state should be legal, and if you have a problem then you should apply diplomatic (ultimately military) pressure? Sounds like a recipe for atrocities and then war (like in nazi Germany). It's unfortunate that the high level sociopaths will probably get away with it, but we should still prosecute the lower level sociopaths who did the torturing. This will make it hard to order people to do this in the future.
Ask yourself two questions:
Is it ok to kidnap someone, lock them in your basement, beat them and rape them?
Does some shit written on a piece of paper make it ok?
I am saying that if the state said something is legal, it should not then prosecute people for having done it while the state was saying it is legal. If you have a problem with what another state is doing (and you are a state), then you should apply diplomatic/military pressure; I do not know what other recourse you have.
In this case, what was done is illegal under international law, and was illegal under international law at the time it was done, so people can be tried in international court without ex post facto concerns.
I am one of those people who disagree with the Nuremberg trials. If something atrocious happened, but was legal, then we should make it illegal and accept the fact that some people got away with doing horrible things.
Ask yourself two questions:
Is it ok to kidnap someone, lock them in your basement, beat them and rape them?
Does some shit written on a piece of paper make it ok?