War is not an end in itself. It can only ever be justified as a means to achieve some specific objective, and the wisdom of a decision to go to war must be judged accordingly. What is the objective? Can it be achieved? At what cost, and is the objective worth that cost? National leaders have a duty to weigh these questions carefully before deciding for war.

Scott Morrison should be thinking deeply about all this, because if war breaks out between America and China, which is a real possibility, he would face the gravest decisions that any Australian leader has had to make since 1939. He acknowledged this himself last year when he aptly compared today’s strategic risk with the late 1930s.