The history of the 20th century usually comes packaged in two parts. The post-war period after the end of the Second World War, and the earlier pre-war period. While the two are easily distinct there are also common threads that run through both of them and conceivably connect them into one whole. One such thread is an arms race dynamic. Most of the 20th century, beginning in the 1930s at the latest, along with our own time in the 21st, conceivably tells a story of a single uninterrupted arms race.
Clearly, the timeframe of the Great War from 1914 to 1918 was a period of militarism and unprecedented global buildup of arms. It saw the rise of economic regimentation and the subordination of economic activity to the immediate needs of the state, as well as of the view that saw the usefulness of production primarily in giving a nation the ability to wage an extended industrial war.
Following the end of the Great War military expenditure fell sharply and receded to levels that did not seem a cause for alarm. However, the experience of the war could not simply be erased. Even as the size of armies was reduced old thinking remained and influential circles continued to think of the economy as another branch of the armed forces. According to this thinking the usefulness of bountiful agricultural and industrial production lay primarily in the fact it granted a nation the ability to raise, feed, equip and maintain a military that was as large and as mechanized as humanly possible. This, the experience of the First World War had shown, was the first prerequisite to avoid national disaster and national humiliation, as had befell Germany, Russia, Turkey and Austria-Hungary.
In this way even after the Great War had ended its shadow continued to loom, as its lessons continued to inform participants and non-participants alike. Japan for example had seen that a major cause of German defeat in the war had been its inability to feed its population from its own agricultural production. For all its industrial might Germany had in fact not been capable of an extended industrial war. Once the British established their maritime blockade and cut off Germany from its imports the populace of the latter had been placed on the path leading to slow starvation.
The Japanese knew that being even less self-sufficient than the Germans, they were even more vulnerable to blockade than had been Germany itself. Being therefore categorically incapable of an extended war in a serious conflagration Japan was no true independent power capable of autonomous action on the world stage. To truly become such it would need to field a large, sophisticated army and navy, but also be able to produce, or extract sufficient quantities of everything it needed, whether it was foodstuffs, ore, oil or machinery, in the confines of its own borders. The quest for military power, was therefore inseparable from the quest for autarky.