A distant view, with little knowledge of the geopolitics of the area, questions why would a deterrent be required. Speculative aggression - who is from the North, but why, what is to be gained.
Do they seek space - GAFA, there’s plenty of sunshine energy there, similar to the outer reaches of China.
Resources, not necessarily to own them, but to isolate or minimise world supply to an aggressors advantage. The physical destruction or strategic isolation of Oz would be an immense, if not impossible task, thus consider some form political isolation with threat; how, has this been done before, geographicaly and time scales.
Don’t discard any U.K. input, we respect and remember friendship, our word is our bond, treaties are upheld.
Seeking deeper understanding.
However, anticipating this might be in short supply for the next few hours - Edgbaston, or even longer depending on the result, a lesson might be how to play ‘spin’ on a sticky wicket; sport or politics