Readers of this book must keep reminding themselves that, despite the fantasies it describes, it is not science fiction. Its characters are real people contending vigorously over threats they see as real. When the perception of such a threat fades--of war with the Soviet Union, for example--or disappears, like the Soviet Union itself did, another appears. Now we have the China threat and threats posed by "rogue states" (recently renamed "countries of concern"). When a vast, impenetrable, space-based shield designed to thwart enemy attacks proves unfeasible, space warriors invent replacements--something called "Brilliant Pebbles," for example.