Patriot Advanced Capability-2
The Patriot Advanced Capability is the oldest ballistic missile defense system of the U.S. Army. It was originally designed in 80's as an air-defense system, but the mission was eventually extended to counter short-range (also known as theater) ballistic missiles. This mission has eventually become primary.
Balllistic missile defense system features track-via-missile guidance system that allows its radar to steer it toward the target - incoming ballistic missile. In the terminal phase of the flight the Patriot missile transmits target's position updated data to the ground stations and the command and control center sends back to the Patriot interceptor correction calculations. Corrected data enables the Patriot interceptor to destroy incoming missile. Usually the speed of both the ballistic missile and the Patriot missile exceeds 5,000 km/h.
The Patriot interceptor is supplied inside an aluminum canister that acts as a launch tube and storage container which enables rapid deployment - a battery-sized element can be emplaced in less than an hour.
The Patriot Advanced Capability-2 was developed due to the low performance of the original interceptor during the First Gulf War in 1991. However, we need to bear in mind that it was air-defense, not ballistic missile defense, system. The system is under continuous improvement and eventually have featured greater range, better warhead, enhanced guidance system and better performance against ballistic missiles, aircraft and cruise missiles. The U.S. Army is supposed to deploy up to 52 Patriot Fire Units with 791 Interceptors. The aging technology should be replaced by the Medium Extended Air Defense System developed jointly with Germany and Italy.