"It is, not to put too fine a point on it, a piece of propaganda," he told the convention.
"It is a reminder to people who seem to have forgotten who we're up against."
According to SkyNews.com, Miller said that he wants Batman to "kick Al Qaeda's ass".
In justifying his project, he said that it wasn't unusual for a graphic novel to feature real-life villains.
"Superman punched out Hitler. So did Captain America. That's one of the things they're there for," Miller said.
SkyNews.com reports that the graphic novel, already half finished, will appear next year.