Now I Get It: How the U.S. could stop a nuclear missile from North Korea

Despite North Korea's agreeing to participate in the 2018 Winter Olympics in PyeongChang, South Korea, the country is still moving forward with developing an intercontinental ballistic missile capable of reaching the U.S. mainland. The Ground-based Midcourse Defense system, or GMD, is designed to detect, intercept and destroy such long-range ballistic missiles. How does it work?