Australia's Head of State is the Queen of the United Kingdom(and other commonwealth realms).

The Queen of the UK is the OFFICIAL HEAD OF STATE of the following countries

Antigua and Barbuda, Australia, The Bahamas, Barbados, Belize, Canada, Grenada, Jamaica, New Zealand, Papua New Guinea, Saint Kitts and Nevis, Saint Lucia, Saint Vincent and the Grenadines, Solomon Islands, Tuvalu, and the United Kingdom.

So, while Australia may not pose a threat... the combined might of the Holy United Kingdom Monarchy certainly does.

The UK Monarchy has paid millions in propaganda to minimize the perception of their power. You may hear that being the official head of state of a country means nothing. And, you may believe it... many knighted political scientists, newsman, and academics have claimed the same thing.