Terminal High Altitude Area Defense (THAAD), formerly Theater High Altitude Area Defense, is a United States Army system designed to shoot down short, medium, and intermediate ballistic missiles in their terminal phase using a hit-to-kill approach. The missile carries no warhead but relies on the kinetic energy of the impact. THAAD was designed to hit Scuds and similar weapons, but has a limited capability against ICBMs. [citation needed]