Robert D. Kaplan

Given the level of anti-Americanism in the world, given the level of frustration with the United States throughout the Muslim world, you've got a homegrown attack or you have a nuclear explosion in the air that is not a test somewhere. Those are still the biggest threats out there.

The historical novelist has to consider what has actually happened, while the SF writer is dealing in possibilities, but they are both in the business of imagining a world unlike our own and yet connected to it.