Terminal High Altitude Area Defense (THAAD)

Terminal High Altitude Area Defense (THAAD) is a transportable system that intercepts ballistic missiles during their final, or terminal, phase of flight. It incorporates an X-band radar, the AN/TPY-2, and a single-stage, hit-to-kill interceptor to defeat ballistic missiles inside or outside of the atmosphere.

THAAD occupies a middle tier in the United States’ Ballistic Missile Defense System (BMDS), covering a larger defended area than the Patriot while serving as an underlay for the exoatmospheric Aegis BMD and GMD systems. In flight tests, it has demonstrated capability against short-, medium-, and intermediate-range ballistic missiles.

THAAD development

In response to Congressional calls for a “deployable TMD demonstration system,” the Army began developing THAAD, which entered Program Development and Risk Reduction (PDRR) in 1992.¹ The Army first test launched a THAAD prototype in April 1995. On December 13, 1995, the Army attempted its first THAAD intercept test, which was unsuccessful. Five successive flights—taking place from 1996 to 1999—also failed, largely due to “quality control deficiencies in the manufacturing of the interceptor.”²

Despite two successful flights in June and August 1999, the Army elected to redesign THAAD and relax its requirement for intercepting targets at lower altitudes. THAAD subsequently entered Engineering and Manufacturing Development (EMD) in June 2000.

Date	Name	Outcome	Notes
April 21, 1995	FT-1	N/A	Propulsion test, no target launched
July 31, 1995	FT-2	N/A	Kill vehicle controls test, no target launched
October 13, 1995	FT-3	N/A	Target flyby test; no intercept attempted
December 13, 1995	FT-4	Failure	“Premature kill vehicle fuel consumption” due to software error
March 22, 1996	FT-5	Failure	Failed kill vehicle separation
July 15, 1996	FT-6	Failure	Seeker failure; half of focal plane array malfunctioned
March 6, 1997	FT-7	Failure	Divert thrusters failed to fire due to battery connection failure
May 12, 1998	FT-8	Failure	Booster failure after electrical short circuit from foreign object debris
March 29, 1999	FT-9	Failure	Attitude control system nozzle torn from bracket
June 10, 1999	FT-10	Success	Intercepted HERA unitary target
August 2, 1999	FT-11	Success	Intercepted HERA separating target

In its EMD phase, the THAAD intereptor prototype was redesigned to feature more powerful thrust vector control and divert systems, improved computers, and simplified avionics.³ The THAAD EMD missile passed critical design review in December 2003 and the first AN/TPY-2 radar was delivered in March 2004.⁴

This “next-generation” interceptor underwent its first flight test on November 22, 2005 and its first intercept test on July 12, 2006, where it successfully intercepted a ballistic missile target.⁵ Between 2006 and 2019, the Army and Missile Defense Agency conducted 18 THAAD intercept tests. 14 of these tests were successful and 4 were cancelled before launch due to target malfunctions.⁶ The production THAAD system has not failed an intercept test.

November 22, 2005	FTT-01	N/A	Propulsion test, no target launched
May 11, 2006	FTT-02	N/A	Demonstration of THAAD radar, launcher, fire control operations against simulated target
July 12, 2006	FTT-03	Success	Intercepted unitary target; seeker characterization flight
September 13, 2006	FTT-04	N/A	Target malfunctioned; no-test declared
January 26, 2007	FTT-06	Success
April 5, 2007	FTT-07	Success
October 26, 2007	FTT-08	Success
June 25, 2008	FTT-09	Success
September 17, 2008	FTT-10	N/A	Target malfunctioned; no-test declared
March 17, 2009	FTT-10a	Success
December 11, 2009	FTT-11	N/A	Target malfunctioned; no-test declared
June 28, 2010	FTT-14	Success
October 4, 2011	FTT-12	Success	2 targets launched; both intercepted
October 25, 2012	FTI-01	Success	MRBM-class target
September 10, 2013	FTO-01	Success	MRBM-class target
October 4, 2015	FTO-02 Event 2	N/A	Target malfunctioned; no-test declared
November 1, 2015	FTO-02 Event 2a	Success	2 targets (SRBM and MRBM); both intercepted
July 11, 2017	FTT-18	Success	First intercept of IRBM-class target
July 30, 2017	FET-01	Success	MRBM-class target
August 30, 2019	FTT-23	Success	MRBM-class target

THAAD components

THAAD incorporates four main components: the interceptor, launch vehicle, radar, and fire control system.

THAAD interceptor

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The THAAD interceptor is 6.2 meters long, 0.4 meters in diameter, and weighs 662 kg at launch.⁷ It consists of single-stage, solid-propellant booster and a liquid-fueled kinetic kill vehicle. The missile’s booster is constructed from carbon fiber and uses a hydroxyl-terminated polybutadiene (HTPB) propellant. It employs a thrust vector system for control and a deployable rear flare for stability.⁸ The THAAD kill vehicle is constructed from composites and uses a gimbaled infrared seeker to track targets in the terminal phase.⁹ After approaching the target with its main booster, the THAAD kill vehicle separates and uses its hydrazine-powered divert thrusters to maneuver in its final trajectory.

The THAAD system defend targets at ranges of 150 – 200 km.¹⁰ Unlike other missile defense systems, THAAD can intercept targets within (endoatmospheric) and outside (exoatmospheric) the atmosphere.¹¹

THAAD launcher

The THAAD launcher is based on a 4-axle heavy expanded mobility tactical truck (HEMTT). Each launcher carries up to eight interceptors, which are housed in 6.6 m long, 1,044 kg launch canisters.¹² There are eight interceptors per launcher. A typical THAAD battery includes 6 launchers, and each launcher takes up to 30 minutes to reload.¹³

AN/TPY-2 radar

The THAAD system utilizes the Army Navy/Transportable Radar Surveillance (AN/TPY-2) radar to detect and track enemy missiles at ranges of 870 to 3,000 km.¹⁴ The AN/TPY-2 radar is deployable in two modes: a forward-based mode (FBM), where it detects missiles in the ascent phase to cue other BMDS elements, and a terminal mode (TM), where it provides tracking and engagement data for terminal THAAD engagements.¹⁵

The AN/TPY-2 radar includes four major subsystems: the main antenna, or Antenna Equipment Unit (AEU), the Electronic Equipment Unit (EEU), the Cooling Equipment Unit (CEU), and the Prime Power Unit (PPU).

The AEU is the main radiating element of the AN/TPY-2 and operates in the X-band. Its high operating resolution allows it to more effectively cue engagements and discriminate targets from decoys and debris. The trailer-mounted system has a 9.2m^2 phased-array antenna face with over 25,000 antenna modules.¹⁶

Three other trailers—the EEU, CEU, and PPU—provide the requisite processing, refrigerated coolant, and electrical power to continue operations. The antenna and electronics units connect with THAAD fire control elements with fiber optic cables, and the cooling and power units feed chilled coolant and power to the other radar subsystems.

THAAD Fire Control and Communications System

The THAAD Fire Control and Communications (TFCC) component oversees battery operations and relays fire control information to other elements of the joint force. Each system, known as a Tactical Station Group (TSG), incorporates a Tactical Operations Station (TOS) with two operating stations, a Launch Control Station (LCS), which includes wireless datalinks, networking equipment, and fiber optic cable interfaces, and a Station Support Group (SSG) which includes HMMWV-based antenna and cable support vehicles.

Operating in concert, these systems control battery launch operations and transfer fire control information from the AN/TPY-2 radar to the larger Command, Control, Battle Management, and Communications (C2BMC) network. By connecting with C2BMC, THAAD can exchange tracking data with Aegis, GMD, and Patriot missile defense. MDA first demonstrated a THAAD-cued Patriot intercept in 2020.¹⁷

Service history

The Army initially fielded THAAD in April 2012 with two batteries at Fort Bliss, Texas.¹⁸ To facilitate the training of the future THAAD force, the Army opened a training center at Fort Sill, Oklahoma in 2015.¹⁹

By the end of 2015, five THAAD batteries were active.²⁰ As of 2019, the United States fields seven THAAD batteries and has deployed three outside of the continental United States, including in Guam and South Korea.²¹ The United States fields additional FBM AN/TPY-2 radars at Kyogamisaki, Japan; Shariki, Japan; Kürecik, Turkey (Site K); Mt. Keren, Israel (Site 512); and at a fifth, unknown, site, likely in Saudi Arabia (Site 4a).²²

In 2013, the Army deployed a THAAD battery to Guam in response to North Korean threats to the island.²³ On May 1, 2017, the Army activated its first THAAD system in Seongju, South Korea.²⁴

In April 2019, the United States temporarily deployed THAAD to NATO’s European Phased Adaptive Approach (EPAA) site in Deveselu, Romania as its Aegis Ashore system received maintenance.²⁵ Following drone and missile attacks on Saudi oil facilities, the United States deployed a THAAD battery to Saudi Arabia in October 2019.²⁶ This system was withdrawn in mid-2021.²⁷

Foreign operators

In 2012, the Defense Security Cooperation Agency (DSCA) approved the sale of THAAD to Qatar and the United Arab Emirates, the first foreign military sale of the weapon.²⁸

In 2013, U.S. contractors concluded an initial agreement, valued at $1.135 billion, to supply two THAAD batteries to the UAE. The sale reportedly included up to 192 interceptors, 2 AN/TPY-2 radars, 12 launchers, and other support systems.²⁹ By late 2015, 81 UAE servicemembers had completed THAAD training.³⁰ The UAE activated its first batteries some time in 2016.³¹

On October 6, 2017, the United States cleared the possible foreign military sale of up to 7 THAAD batteries to Saudi Arabia for an estimated cost of $15 billion.³² U.S. and Saudi officials signed formal terms of sale in November 2018. In April 2019, Lockheed Martin was awarded an initial $2.4 billion contract for THAAD interceptors, and received an additional $1.48 billion award in July 2019.³³ In March 2020, Lockheed received a $932 million contract modification for THAAD interceptor production, and, in April 2021, an additional $611 million for support services.³⁴ In addition, Raytheon Technologies received a $2.3 billion award for the sale of seven upgraded, gallium nitride (GaN)-based AN/TPY-2 radars in June 2020.³⁵

On November, 5, 2012, the United States approved the possible sale of up to 2 THAAD batteries to Qatar for an estimated cost of $6.5 billion. The proposed sale would include up to 12 launchers, 150 interceptors, 2 fire control systems, 2 AN/TPY-2 radars, 1 Early Warning Radar (EWR), and associated equipment.³⁶ Due to budget and operational challenges, the sale was not finalized.³⁷