I think we have a problem here

and the name of that problem is Neil Prakash and those like him.
Perhaps I should start a little earlier than Neil Prakash though and say something else.
I have never felt any sympathy for David Hicks. He was not a "misguided young man" as some have sought to portray him. He didn't make one or even two decisions that led to his stay in Guantanamo Bay's detention centre. He made many decisions. He made many wrong decisions. He went to Kosovo as well as Afghanistan. He didn't need to do any of the things he did. 
Mercenaries are not "soldiers" in my book. They are people who are seeking "excitement" of the worst possible sort. 
Hicks could have stayed home and found his adrenalin rush doing something like sky-diving. He doesn't need sympathy and, in the end, he got off leniently.
He got off leniently because he didn't lose his citizenship. If there had been a way of doing it then many people may have believed it would be a desirable outcome.
Having said all that I would also like to say that I don't believe that places like Guantanamo Bay are the answer either. I have no idea what you do with such people, the worst of whom are so incredibly dangerous that locking them up for life seems to be the only solution people have come up with to date - at least, the only one which does not involve some sort of medical intervention.
And that brings me to Neil Prakash who went to fight with ISIS and tried to encourage others to commit terrorist acts here. He is currently languishing in a Turkish gaol and there is an extradition warrant out for him when he finishes his time in that one. 
There has been an attempt to strip him of his citizenship. It is not likely to succeed. The law here says you must be a citizen of another country. Stripping of citizenship can only occur if you are not going to be rendered stateless. It might not have solved the problem even if it did succeed because it would cause a rift in relations with one of our neighbours.
Prakash, and those like him, who join organisations like ISIS and other terror related groups represent a major issue for countries like this one. Yes, if they have dual citizenship we can legally send them to their other country. But, and this is a real problem, in all likelihood, the other country won't want them either. Who can blame them? Sending someone to a country they left when they were perhaps just a toddler and where they don't speak the language or have any support networks also means that they are either going to continue their life of crime or become welfare dependent.  It can rouse sympathy for their cause too.
Lock them up here and there will  be those who support them  who waste days, weeks, months and even years of the court's time trying to have them freed. They will claim they are political or religious or some other sort of "victims". If they are released at any point they won't be able to get jobs and , unless kept in isolation, will encourage others to carry on  their "work". 
I was discussing all this with Ms W yesterday. She has just come back from holiday on the island to the south of our state. For some reason the topic is one she had given some thought to. Eventually she said,
      "You know it really would be sensible if they found an island which was too far for them to escape. You could put them all there together with food and stuff to build things to live in. Once a month a plane could go past and drop more stuff to eat. You wouldn't let them have the internet or anything like that but they could maybe have some books to read and board games. They'd have to work together if they wanted to stay alive. "
The conversation got interrupted at that point but, as she went out the door, I thought, "Something like Pitcairn Island perhaps? Even St Kilda might do."