They were offered nonjudicial punishment. Since they refused they will automatically receive a courts-martial.
There are other charges such as giving a false statement and obstruction of an investigation.
They may get off of the assault charge but the other charges I’m not so sure.
Merely denying you did it is now enough to trigger false statement and obstruction charges. Don’t read too much into what they are charged with. It is far more useful to look into the motive of the terrorist prisoner. It is exeedingly easy to give yourself a bloody lip if properly motivated. These terrorists train for capture, and know what they need to do to get the .mil to throw charges against their captors. The fact that the higher ups in the military haven’t caught on to this game (even though we have the training manuals the terrorists have produced!) continues to strain credulity.