You release Prisoner's of War when the war is over. Not until then.
As a Prisoner of War, these illegal combatants would have certain limited rights and the retaining country would have specific responsibilities as outlined in the Geneva Accords. However, the Geneva Accords deal with relations between countries which are signatories to the Accords.
If someone expects to invoke the Geneva Accords as a protection or grounds for complaint, they must have behaved in manners outlined in the earlier chapters of the Accords which include being a part of an organized military service, wearing of identifiable uniforms, avoidance of wanton disregard for the safety of noncombatants, etc.
The combatants held in the Guantanamo stockades were members of
guerilla groups, wore no uniforms, violated protections of noncombatants and generally fail all provisions of the Accords which would have classified them as prisoners of war. Thus, the characterization as illegal combatants.
If someone believes these few retained personnel at Guantanamo stockade are simple soldiers, you probably also buy the contention that Mr. William Jefferson Clinton is qualified to be President of the United States. These were classified as high-value members of the combatant organizations following field interrogations. They are being held because they are believed to hold information on the membership, organization, leadership and plans of these groups. They are not being held because they broke international laws and need to be tried in a court of law.