Rod Lurie came up with the film's idea after spending a lot of time watching CNN at home while writing a few other scripts. When he saw that there had been serious crises involving both Iraq and North Korea that happened some time from each other and both nearly resulted in war, he thought it was a good basis for a film about how multiple same time international crises could lead to impossible choices for a U.S. President.
The trivia item below may give away important plot points.
In the original script, President Emerson did not know that the Iraqi nuclear missiles were useless, and delivered and carried out his ultimatum aware that it could cause massive nuclear strikes around the world. The screenplay was changed to have Emerson fully aware that the U.S. and France had set up Iraq to acquire worthless nukes so they wouldn't pursue an effective homegrown nuclear program.