Australia and NZ have some of the toughest immigration laws anywhere, and the woman leader they had told them not to come there, if they could not live as the Australians do....so the only objection should be PRO GUN LAWS and teaching every citizen to arm themselves and how to use the guns. The terrorists do not go to these countries legally. Just like criminals do not buy guns legally either.
And, for even more safety: TWO big Rottweilers, TWO big German Shepherds or TWO big any-dogs GUARDING the homestead will stop anyone COLD. THAT is what doggies DO.
The bad guys will hear the barking, get outta Dodge...and move on to a much more quiet, dog-less house.