Reading the comments too.
I want to comment there, but I'm a bit intimidated by the company.
We have a serious problem.
They were captured under arms.
If they're POW they sit in a prison camp until the conflict is over. For as long as that may be regardless of how many elections we have and who wins them. Geneva and Hague agree and was reinforced after WW2 when we got huffy about the Soviets NOT releasing German POWs.
If they aren't POW then they are non-entity and can be disposed of as we will. You may notice that not a single German was at Nuremburg for what happened to partisans?
The traditional method is to summarily to shoot them. Other methods have been employed to cow the local populace, but killing them outright is acceptable.
Keeping indefinitely in a decent by American standards prison is far less than death, so it's got to be OK.
Torture is another matter, but that's got little to do with holding people who were captured under arms.