I don't particularly fear invasion by China as Australia has...

I don't particularly fear invasion by China as Australia has maintained a
reserve capacity to build nuclear weapons since the 1960's.

The decision was taken back then to have the ability to assemble atomic
bombs with about a year's notice, because of our fears of the 'domino
effect' in SE Asia, that a new isolationism was creeping into America
with the opposition to the Vietnam War.

It is why we keep Lucas Heights well funded even though Australia has
no nuclear energy industry. In gov't warehouses spread across the country
would be enough material for say a dozen warheads (i got no idea
how they would deliver it, maybe we bought some missiles along the way)

We couldn't wipe out China if they invaded but taking out 100m folks
in their biggest cities is quite the deterrent.

The only prob i see is a limited war in Taiwan, particularly if it is
due to nationalistic fervour in China (Falklands-style pick a little fight
to rally citizens around the flag). America comes to Taiwan's aid,
and we unfortunately form up alongside them. The Chinese may not be
historically imperialist but they are as ardent a flagwaver as any,
and Taiwan is considered by all to be part of China.