THAAD (Terminal High Altitude Area Defense) is a mobile system is meant to destroy incoming missile warheads in their terminal phases. Since these warheads would be destroyed over friendly territory the THAAD missile works using a direct hit instead of proximity explosions—the kinetic kill—to not disperse the warhead materials wider than minimally possible.
X-band radar (microwave frequencies from 7–11.2 GHz) ground units guide the 125 mile ranged missile with an altitude capability of 93 miles. The ER (extended range) version, if development is successful, promises to be useful against hypersonic glide vehicles.
The speed of incoming warheads, as well as hypersonic glide vehicles, make shooting them down a machine-v-machine affair as there is a matter of ten seconds or less to acquire, launch and kill the incoming threat.