Could a president’s  overconfidence in U.S. defensive systems lead to deadly miscalculation and nuclear armageddon? Yes. Yes, it could. Last Wednesday, referring to potential American responses to North Korea’s missile and nuclear program, President Donald Trump told Sean Hannity “We have missiles that can knock out a missile in the air 97 percent of the time, and if you send two of them it’s gonna get knocked out.” If Trump believes — or is being told — that American missile defenses are that accurate, not only is he factually wrong, he is also very dangerously wrong. This misperception could be enough to lead the United States into a costly war with devastating consequences.