Compared to boost-phase and terminal missile defenses, exoatmospheric ballistic missile defense (BMD) is the most difficult of all missile defense mission sets. It requires launching a hypersonic missile interceptor to shoot down another hypersonic missile in space. Hit-to-kill interceptions, such as those performed by the DN-3 and the American SM-3, are even more technically demanding. They require the interceptor vehicle to precisely smash into the incoming warhead in order to destroy the missile with force of impact alone. It's such a difficult task that early BMD missiles like the LIM-49 Spartan used a nuclear warhead to overcome fire-control issues.