DARWIN, Australia—The past casts a long shadow over this palm-lined city on Asia’s fringe.

In February 1942, a devastating Japanese airstrike killed more than 200 people here and prompted many more to flee into the remote Outback. Together with the fall of Singapore days earlier, the attack on this “wild little tropic port,” in the words of U.S. war correspondent John Lardner, forcing a fundamental change in Australia’s outlook that its remoteness bestowed a level of safety from the world.

Three...