It doesnt matter where they are - they still retain their Humans Rights.
Either they are sentenced to prison in a court under the respectively applicable law (isnt easy to say which laws apply for them though), or they go free.
I'm not defending their actions or terrorism in general, and i think most of them are detained for a reason - but - nothing of that matters.
Taking someone, without court order, no trial, for an arbitrary long time, is the opposite of the essence and intent of the US constitution, Human Rights, and basically everything a western democracy should be standing for.