And we learn this on December 7, of all days! Seventy years ago, if someone suggested that one day Australia would be asking Japan for submarine technology, that Japan would be America’s friend and China would be America’s enemy, he would be hauled off to the closest lunatic asylum! ;)
Shifting alliances. Given enough time friends will become enemies, enemies friends and then back again.
In the absence of American leadership, long-time American friends will seek help elsewhere.
That's because memories are short. The 100 Years' War killed off between 1/3 to 1/2 of France's population from start to end, with widespread chevauchees (looting and burning of the countryside, along with the occasional massacre) implemented to persuade French troops - usually unsuccessfully - to emerge from behind their fortifications. And of course, France's iconic heroine, Jeanne d'Arc, was burned at the stake by la perfide Angleterre. In comparison, what passes for history between Japan and Australia is a non-event.