Two questions form the foundation of all novels: "What if?" and "What next?" (A third question, "What now?", is one the author asks himself every 10 minutes or so; but it's more a cry than a question.) Every novel begins with the speculative question, What if "X" happened? That's how you start.
Tom ClancyProbably what pushed the Russians over the edge was SDI... They realized they couldn't beat us...
Tom Clancy