Is Australia at risk from a possible Foreign military invasion in the future?

With Australia being a member of both the UN and NATO, I highly doubt that they have any worries of being invaded by another nation. Australia has way too much backup for anyone to be stupid enough to invade them. The US Forces alone would obliterate anyone who decided to attack them, with of course, the exception of China or North Korea. If either of these countries decided to attack, the rest of the world would come together and beat them down. NO WORRIES!!! Plus, Australia has a formidable military of their own with some pretty good fire power. They'd be able to hold off their enemy until help arrived.