How many German or Japanese soldiers were given "due process" during WW2 prior to being held as POWs? In that case, if the person was wearing the uniform of an enemy combatent, then they were presumed to be the enemy, whether they were actively fighting or not.
In this case, there is no formal uniform - that makes it more difficult on us. We can't necessarily identify the enemy on sight. But, if the person is carrying a weapon and fighting US forces, then they are presumed to be the enemy. God help us if the lawyers have to become involved to pass judgement on who the enemy is.
If it looks like a duck, walks like a duck and quacks like a duck, maybe it's a duck. In this case, if the person is shooting at our soldiers, maybe the simplest answer is the correct one - he's an enemy soldier, and if captured, a POW.
Fletcher J
These aren't American citizens. These are prisoners of war. There's no legal system involved, and they have no right to due process, in fact no right to anything other than humane treatment and release at the cessation of hostilities. Yes, that's something the lawyers could fight about.
If I'm not mistaken all those released from Guantanamo have signed a parole agreement, yes a rather 18th-19th century thing, which they've clearly violated. Back in the day, on recapture, they'd be hung, though I'm sure these guys will get free representation.