The New York Times reports that the U.S. government does plan to try to bring some semblance of law back into the picture with regard to KSM:
The base at Guantánamo holds about 385 prisoners, among them 14 senior leaders of Al Qaeda, including Khalid Shaikh Mohammed, who were transferred to it last year from secret prisons run by the Central Intelligence Agency. Under the Pentagon’s current plans, some prisoners, including Mr. Mohammed, will face war crimes charges under military trials that could begin later this year.
"War crime" is maybe the ultimate oxymoron. How can one break the law during a state of war? It is insensible, an abuse of language and meaning. Normally, yes, it can be valuable to signal that certain actions by others will be met with certain responses. However, in war you are already out to kill your enemies without inquiring into their actions; signaling that you will also kill them if they do something really awful does nothing to alter their mental calculus, and thus it does not help to bring about order.
War crime is definitely a useful concept for centralized warfare. It makes
sure that people kept civilians out of war/didn't kill prisoners/etc or
face possible extra consequences later on. Of course, these consequences
only occured if they were on the losing side of the war so they might
discount the punishment by 50% (or higher depending on morale). At the end
of such a war the enemy is more likely to surrender en mass than die en
mass and so warcrimes are something that both sides need to consider. (It
also needed to consider the plain fact that if one side kills or tortures
prisoners of war then others are less likely to surrender, causing more
deaths on both sides - so comitting the crime of mistreating prisoners of
war has other incentives preventing it.)
I agree almost completely; my post took the predominance of "total war" as
a given, which is defensible but probably should have been explained.