What in the hell are you talking about.
You wrote: "Can you go kidnap your neighbor, hold him in your basement for two years, release him and excuse yourself because some group bombed a train in Europe?"
We did not pick these people up at random from the streets of a neutral country. We captured them in the course of fighting a war against the Taliban and Al Qaeda in Afghanistan. Perhaps some were detained in error, but it was in the middle of a war. They either were combattants, or were closely associated with combattants, which is why they were seized.