The premise of the movie doesn't make any sense. There is no pressure to retaliate to a single nuclear missile launched at Chicago within the 18 minute flight of the missile. The only scenario that introduces a minutes-long decision window is if the US nuclear capability is in imminent danger, which it obviously is not from a single missile headed for Chicago. What any person not following a Hollywood script would do is wait few hours for credible intelligence, coordinate with other nuclear powers to avoid escalation, and wipe out whoever conducted the attack. Its a movie that only works if you don't think about it, which is a major problem because it is trying to be thought provoking.