The AN/TPY-2 Surveillance Transportable Radar, also called the Forward Based X-Band Transportable (FBX-T) is a long-range, very high-altitude active digital antenna array X band surveillance radar designed to add a tier to existing missile and air defence systems. It has a range of up to 3,000 km, depending on target/mode. Made by Raytheon, it is the primary radar for the Terminal High Altitude Area Defense (THAAD) missile system, but also cues the AN/MPQ-53 radar of the MIM-104 Patriot system. Patriot PAC-3 is a lower-altitude missile and air defense system than THAAD.