ahmadjee,
There are lots of open threads where this is debated, so I'll summarize quite a bit. But first let's look at some history of POW's. In World War II the Germans captured over 3.2 million Russian prisoners, and only 600k were repatriated at the end of the war, the rest died in German custody. Japan killed nearly half of the 50,000 POWs in the Battan death march. Most of those, as well as over 20k Chinese prisoners were killed because the japanese used the prisoners for live bayonnet practice. So Guantanamo, in the history of POW's, is some very mild stuff indeed.
Essentially POW's in virtually every instance are detained until the end of the war. In some cases there have been prisoner exchanges. The detaining party, at it's sole discretion may offer anmnesty to those prisoners willing to renounce combat. In many wars it is not unusual for POW's to be held for 6 to 8 years. Check the hanoi hilton, this was commonplace in Vietnam.
Some detainees may have also committed crimes, punishable by their home countries, for participating in foreign wars. Thus some detainees may be repatriated to thier home country to face criminal charges. Afghan prisoners can be removed from the field of battle, but can be returned to the custody of the Afghan government, as the current Afghan governemnt was indeed an ally of the US in the conflict. So the question is, would you rather be in Guantanamo, or in a Norhtern Alliance prison. if the prisoners are returned, and suddenly end up dead, is that responsible? Or further, if the prisoners are returned, and are released by corrupt guards, would htis contribute to peace in Afghanistan?
The Geneva conventions are very specific as to who is entitled to it's protections. Please carefully read the conventions and you will find that mercenaries, those paid to fight who are not citizens of the country, or it's allies are specifically excuded from the protections of the Geneva conventions. Also very specifically adressed in the Geneva conventions, are rules on Uniforms, and using civilians, and civilian places for protection. While decrying all of the civilain casualties, people ignore the fact that many casualties were caused because it was impossible to distinguish fighters from civilians. When you do not wear a uniform, you are not entitled to many protections of the Geneva conventions. This is done for the protection of civilians.
Mercenaries are particualrly frowned upon by international law. Your Jihadi is my mercenary. But encouraging willing combatants to decend into a country to fight a war from all corners of the globe, paid by a terrorist organization, is not to be encouraged. You can bet that the existance of Guantanamo is meant as a sign, as a deterent, that mercenary/jihadi's will be imprisoned for long periods, and will not be entitled to legal process. You may not like it, but my degree of compassion for those who travelled to Afghanistan to fight is pretty thin. Dil may see some guy in traditional Arab clothing in a hood, I see some guy who helped to slaughter entire villages in the war with the Northern Alliance, and who was trained at the same camps where terrorists who attacked my country were trained. Thugs and murderers, justified by a thin veil of religion, are still thugs and murders.
I know many military men. The Pentagon has more military lawyers than you can ever imagine. They have assigned lawyers to almost every corner of the military to assure compliance with the laws of war. The place is crawling with them. Guantanamo is a carefully considered legal balancing act that meets the requirements of the rules, while still making a statement about the fate of Jihadi/fighters.
So what do you really think all these citizens of other countries were doing on the battlefields of Afghanistan? Selling girl scout cookies? Building rural health clinics? Crap. They went to fight and kill. Now they are paying a price.
The US is far less concerned with "anti-Americanism" and the PR effects, than putting a stake in the heart of radical violent Islam, and the exportation of fighters to every confilct brewing in the corner of the world.