Unlawful Combatants. Unlawful combatants are individuals who directly participate in hostilities without being authorized by governmental authority or under international law to do so. For example, bandits who rob and plunder and civilians who attack a downed airman are unlawful combatants. Unlawful combatants who engage in hostilities violate LOAC and become lawful targets. They may be killed or wounded and, if captured, may be tried as war criminals for their LOAC violations.
It should be noted that under the treaty provisions, KSM could have been tried and summarily executed in the field as a war criminal. This didn't happen and won't happen because as American Soldiers, Sailors and Airmen (of which I was for 20+ years), we will put ourselves in harm's way to see the war criminal delivered to justice for the Due Process of military law.
The spectre of a "civilian criminal" trial for a war criminal the likes of KSM and his comrades is unprecedented, unconstitutional and an unnecessary risk to the citizens of New York City, or any potential venue for this circus of the insane.