Anyone who collaberates with an invader needs to be killed when the opportunity presents itself. Simple as that. What do you think the French and Norwegians, Poles, Czechs etc did to those who collaberated with the Nazis? It is a basic human behaviour.If Australia were ever invaded I'd be keeping notes as to who was deserving of payback when that became possible, the earlier the better to deter collaberators. Don't forget who is the invader and who is the invaded. The invaded have every right to defend themselves in any way possible, including suicide bombings, IEDs whatever the circumstances allow.
Just remember who the war criminals are and stop defending them. You wouldn't defend the Nazis, so why defend the Americans?