Above all, the “lesson” of the last 150 years since this insular and self-absorbed country was forcibly opened up to the Western world has been that Japanese must be ever vigilant about the vulnerability of their country. As a state that became uniquely dependent upon trade, it has been concerned about securing supplies; and as an island chain of global geopolitical significance, Japan has been concerned about the shifting balance of forces between the great powers. As Kenneth Pyle has observed: