All activities that terrorists do fall under criminal behaviour, and can and should be investigated forensically and dealt with by existing legal systems. It is merely the motive that differs from most other criminals.
If you conspire to, or participate in blowing up people you can be caught and done for completely adequately under Murder or conspiracy to Murder charges. The more people you kill at once doesn't change it from murder. It just compounds the sentence.
Maximum security prisons are deeply unpleasant and totally secure places to hold dangerous people for life, without going so morally ruinously far as to actively torture the inmates. Death penalties in places with death penalties surely account for the rest.
The Bali Bombing a while back that killed 200 people, 90 of whom were Australian? Australia offered a contingent of forensic police to assist the Balinese authorities, which were accepted. Within 3 weeks the Balinese police had arrested about 15 people. They were tried, jailed and some of them executed.
If Soldiers have gone in to a situation, the people they capture are all covered by the Geneva conventions unless they hand them over to the police for a more permanent solution. If you've got a legal problem that is too much for your system to handle, then you bump up your police and justice funding.
Making people disappear without trial, and torturing them, only creates more enemies. Putting people on trial, and convicting them of crimes, and punishing them in a graded way for graded offenses, is MUCH more hard to argue with.
America doesn't have to process every criminal itself. It can rely on other nations. Where it can't rely on other nations, it can rely on the World Court, which specializes in nasty chaotic war zones. If it wants to or needs to, it can pull in through extraditionary type measures overseas criminals to prosecute in America, if those criminals have harmed or provably have taken steps to plan to harm American citizens or their property.
Edited, Feb 5th 2009 8:38pm by Aripyanfar