How does the author use foreshadowing in Debt of Honor?

In the novel's Prologue, we are introduced to what seems to be an era of international peace and prosperity, there are hints that all is not well, and the effective use of foreshadowing entices the reader onward. What, for example, is the significance of Yamata's purchase of land on Saipan, a purchase that results in Japanese ownership of just over fifty per cent of the island? The fact that he is also building nuclear warheads, at a time when the rest of the world is disarming, should alert the reader that all is not well.