As Australia is not at war, then any person residing in Australia should be free to visit any country that they wish to, regardless of the politics/whatever of that country, and without any penalty on their return.
What they choose to do in countries that they visit is their business and unless they commit a crime there that that country wishes to charge them over, then we should only help if there is a treaty in place.

No country can be considered free that penalizes its citizens for the commission of something that is not a crime under its own laws.

Is Mise,
First it is a crime to engage in military actions in another country.
This is a very old law and came about because it compromises the
neutrality of the passport country.
I think it is called the Foreign Incursions Act.

Secondly, what makes you think we are not at war ?
As I said earlier we need a new definition of war.
The war we are currently in has been going on & off for 1400 years.

Is Mise,, these are not your true blue Aussies we're talking aout, these are extremists who call Australia home, simply because of our overly generous welfare system, and, because no other country is stupid enough to give them so much for so little in return.

These are scum bags of the lowest firm and if I had my way I would boot them out either way.

There is no place in our peace loving country for these types of scum and their crap.

Bazz,

"Secondly, what makes you think we are not at war ?
As I said earlier we need a new definition of war...."

That's why we are not at war.

Rechurb,

The Foreign Incursions Act never stopped Australian Military personnel, who were seconded to the British Army, from doing a few days/weeks active service in Northern Ireland, or anywhere else, to gain a bit of experience.

Regardless of the Act, an Australian citizen should be able to go wherever he or she likes without Government interference, if they change their security status by so doing then it is on their own head.

Is Mise, irrespective of the definition, while IS has not stated;
"A state of war exists between Islamic State and Australia."
All the rest of their public statements are equivalent.

So far governments have decided to ignore those statements because to
recognise them would be equivalent to acknowledging IS as a government.
Which of course is another argument for redefining war.

Yep all Ozzies should be allowed to go anywhere they desire, provided they take full personal responsibility for the consequences of their choice of destination. No crying that the Oz government is not doing enough to help them when they have stuffed up.

They should also have their passports cancelled, & never be allowed to return, if they go to any place declared off limits, or no return, by the government of the day.

We have no right to stop people doing anything they want, as long as it harms no other. When it has any potential to harm others, no matter how slight, personal choice, must be removed, & be replaced by public good.