ZenBeam - I am going to wade in here, as it was explained to me, a POW can expect no better treatment than what could be given to their captors. For example, you can’t be fed nothing while your captors eat steak, but neither can you expect steak if your captors are eating gruel.
That’s how it was explained to me. If I’m mistaken, please correct me. 
Also, I am not sure, but the Genevan Convention is only applicable to countries that have signed it. Is that correct?
While our current military operation in Afghanistan looks a lot like a war, it is merely the first stage in a larger operation that has only a passing resemblance to what we’ve called wars in the past. To differentiate, we have no intention of annexing or taking long term control of Afghanistan. If they won (as if), the Taliban wouldn’t be planning to come here and take over. Likewise, the enemy in this operation is not a nation or country but a diffuse international group unaffiliated with any real country. That in itself makes the old definition of war non-operative. We’re on new ground here and will have to make up new rules along the way.
IANAE but I predict most of the Afghans will likely be released once a new government is in place in Afghanistan. It’s a good gesture to the Muslim world and they will be needed to help rebuild their country. The faster they can get back to their schools, farms and businesses, the better for everyone.
There are a few of them who will remain a threat to the rest of the world and should be held. They along with any non-Afghan prisoners taken in our current ops will or at least should be held until over-all victory is pretty certain. How to do that is a real quandary though. US law doesn’t have any real jurisdiction and international law isn’t up to the task from what I’ve seen. I suspect we’ll see some new classification for them such as threats to world peace (TWPs?) and they’ll be held in some place like Belgium for as long as necessary.
Even the ringleaders are in a whole new category. Can you imagine anyplace in America (or most anywhere else) where Osama bin Laden could get what we’d normally call a fair trial?
The best analogy I see for this whole business is a law-enforcement operation in which the military is used as enforcer simply because no one else is capable of handling the job. Even that is not a very good analogy though.
In the James Bond movies, all the bad guys have the good grace to go down with their volcano fortress but I don’t think we’ll be as lucky. Where’s 007 when you need him?
Well, Afghanistan signed the original Geneva Conventions in 1956, and the United States did in 1955. Afghanistan, of course, has undergone several changes of government since then, but evidently no Afghan government has formally withdrawn from the Conventions. (At least, the International Committee of the Red Cross doesn’t indicate such.) Of course, the Taliban was never recognized as the legal government of Afghanistan by the U.S. or the U.N. or most of the states of the world, which adds another wrinkle.
Japan and Russia have never signed a peace treaty. There are still the Northern Islands issue to be resolved, among others.