They don't qualify for the protections provided under the geneva convention so giving them a tribunal is more than they should get. Under the Geneva Conventions, soldiers who fight out of uniform or commit ... murder prisoners or target and kill non combatants may be shot by firing squads.

Under the Geneva Conventions, soldiers who fight out of uniform or commit ... murder prisoners or target and kill non combatants may be shot by firing squads. Sounds like the answer to me