For a large portion of the postwar period, and with very few exceptions such as the Korean War, Japan managed to avoid the direct experience of geopolitical risk. However, this idyllic state of affairs is coming to an end.

"Geopolitical risk" refers to the types of risk that are borne of certain immutable factors, such as geography or history, and which wield enormous influence over national strategies and foreign policy. Other important geopolitical factors include products such as oil or other scarce resources, which can only be extracted from certain soils or regions, and national characteristics such as population, which can only be altered over long periods.

There has been no change to the fact that the Korean Peninsula and Taiwan represent the most important geopolitical factors concerning Japan. In any attempt to defend the country, checking an enemy invasion before it reaches the main islands of Japan — in other words, thwarting an invasion through the forward deployment of troops — makes preventing these two areas from falling under enemy control, at the very least, a matter of life-or-death importance. This geopolitical certainty has remained unchanged throughout the course of Japan's long history.