Ground-Based Midcourse Defense

GMD is administered by the U.S. Missile Defense Agency (MDA), while operational control is provided by the U.S. Army, with support functions provided by the U.S. Air Force and U.S.

GMD after its renaming in 2002 remains a limited defense system, intended to protect the continental United States from limited launches of ballistic missiles. Examples given in the past have included countries such as North Korea. GMD has undergone some controversy over its operational lifetime, such as with a study in 2000 by the Union of Concerned Scientists and the Security Studies Program at the Massachusetts Institute of Technology concluding that "[a]ny country capable of deploying a long-range missile would also be able to deploy countermeasures that would defeat the planned NMD system." Countermeasures studied in detail were bomblets containing biological or chemical agents, aluminized balloons to serve as decoys and to disguise warheads, and cooling warheads to reduce the kill vehicle's ability to detect them. Currently, the Union of Concerned Scientists maintains that GMD is "unproven, unaccountable, and unhelpful for reducing the nuclear threat." More recently, questions have been asked about the Pentagon characterizing the January 28 test in 2016 as a success, when LA Times reported that the EKV suffered a fault in its reaction control system thrusters, which resulted in "a distance 20 times greater than what was expected" according to an anonymous Pentagon scientist. Under the Missile Defense Agency, GMD has conducted multiple test exercises, with mixed results. Early testing revealed deficiencies in the Ground Based Interceptor missile, as well as the Exoatmospheric Kill Vehicle. However, with time, success rates increased, marred by the occasional technical failure such as in 2010's FTG-06 (Flight Test Ground-Based Interceptor) where the Sea-based X Band Radar failed to perform as expected, and the subsequent FTG-06a where despite all elements performing correctly, intercept failed to occur.

Expenditures on the Ground-Based Midcourse Defense program were estimated to be US$30.7 billion by 2007. In 2013, it was estimated that the program would cost $40.926 billion from inception through fiscal year 2017; in 2013–17 spending was to total $4.46 billion, an average of $892 million per year.

• Illustration — A US Exoatmospheric Kill Vehicle from a Ground-Based Interceptor missile destroys a high-altitude target, 2019 • BV: Booster Verification Test • CMCM: Critical Measurements and Countermeasures • CTV: Control Test Vehicle • FTG: Flight Test Ground-Based Interceptor • FTX: Flight Test Other • IFT: Integrated Flight Test

After the FTG-12 test on 11 December 2023, 12 of the 21 (57%) hit-to-kill intercept tests have succeeded. No flight intercept tests from 2010 to 2013 were successful. In response the Pentagon asked for a budget increase and another test for the fielded program. The successful intercept FTG-15 was accomplished by an operational team of the 100th Missile Defense Brigade using their standard operating procedures (round-the-clock 24/7). Although they knew in advance that there would be a test launch, they did not know exactly when it would occur or its exact nature. • Name — date — Result — Description • IFT-3 — This was an element test of the EKV that relied on a surrogate booster vehicle. Because the Inertial Measurement Unit malfunctioned, the EKV used a backup acquisition mode to acquire the target. • IFT-4 — This was the first end-to-end system test, again relying on a surrogate booster vehicle. The test was designed to target a mock warhead, transmitting its location by GPS, and ignore a single large decoy balloon. The failure to intercept was traced to an obstructed cooling line on the EKV that disrupted the IR sensors' ability to cool down to their operating temperatures in time, leaving the EKV unable to detect its target. • IFT-5 — This was the second end-to-end system test. The test was designed to target a mock warhead, transmitting its location by C-band, and ignore a single large decoy balloon. The failure to intercept occurred because the EKV did not separate from the boost vehicle due to an apparent failure of the 1553 data bus in the booster. • IFT-6 — This test repeated IFT-5. The prototype X-Band radar falsely reported a missed target but was confirmed by a satellite, jet, and ground stations. • IFT-7 — This test repeated IFT-6 except that the target booster used Orbital's Target Launch Vehicle instead of Lockheed Martin's Multi-Service Launch System. • IFT-8 — The test was designed to target a mock warhead, transmitting its location by C-band, and ignore both a large decoy balloon and two small decoy balloons. • IFT-9 — Twice delayed from August, this was the first test to use the Aegis SPY-1 radar, although it was not used to achieve the intercept. After the classification of decoys since May 2002, no information is known on their details. • IFT-10 — The failure to intercept occurred because the EKV did not separate from the boost vehicle because a pin broke that should have activated a laser to release the boost vehicle's restraining units. • IFT-13C — Delayed several times from December 2003 due to bad circuitry, this test was designed to use the Orbital Sciences booster from Kwajalein to hit a target from Kodiak, Alaska. The target flew as planned but the booster failed to leave the ground. The failure was traced to a software problem on the 1553 communications data bus, which may be incapable of processing messages at a rate that is fast enough for the GMD system to work effectively. • IFT-14 — This test repeated IFT-13C, with a booster from Kwajalein designed to hit a target from Kodiak, Alaska. Again, the target flew as planned but the booster failed to leave the ground. The failure was traced to the arms that hold the interceptor up in the silo. When they failed to fully retract, the launch was automatically aborted. • FTG-02 — This test involved the first ground-based interceptor launched from Vandenberg Air Force Base to intercept a "threat-representative" target from Kodiak, Alaska. This was the first time that operational radar was used to capture targeting information. Not officially an intercept test, this was originally designed to collect data on the phenomenology of the intercept and act as a radar certification test. No decoys were used. • FTG-03 — With the same setup as FTG-02, the test target flew off-course and an intercept did not occur. • FTG-03A — This test was scheduled in response to the failure of FTG-03, this time with a successful intercept. • FTG-05 — This test launched a threat-representative mock warhead from Kodiak Launch Complex, Alaska followed by a Ground-Based Interceptor from Vandenberg AFB. All components performed as designed. • FTG-06 — This test was to be the first to assess both a CE-II EKV and a complex target scene and the first test to use a newly developed FTF LV-2 target. While the target missile and interceptor launched and performed nominally, the Sea Based X-Band Radar did not perform as expected, and an investigation will explain the failure to intercept. • FTG-06a — This test was similar to FTG-06, over a distance of 4,200 miles. While the Sea Based X-Band radar and all sensors performed as planned, the test was unable to achieve the planned intercept of a ballistic missile target. • FTG-07 — This intercept test used an improved CE-I EKV. • FTG-06b — This test is designed to demonstrate an intercept and meet the unmet objectives of FTG-06a. • FTG-15 — The test involved the new CE-II Block-I version of the EKV, which executed a direct collision with the ICBM target. • FTG-11 — 25 Mar 2019 — This test used two interceptors, one to crash into a dummy target representing an incoming ICBM and another to use sensors to detect another ICBM or other countermeasures. • FTG-12 — 11 Dec 2023 — This test used a CE-II EKV and was the first test of a three-stage GBI operating in a two-stage mode—releasing its kill vehicle earlier by not igniting the GBI's third stage. It was launched from Vandenberg Space Force Base and successfully intercepted an IRBM deployed from a C-17 aircraft over the Pacific Ocean.

• Name — date — Result — Description • IFT-1A — This test allowed the program to assess the Boeing EKV seeker's ability to collect target phenomenological data, and evaluate target modeling and discrimination algorithms for a cluster of 10 objects. • IFT-2 — This test allowed the program to assess the Raytheon EKV seeker's ability to collect target phenomenological data, and evaluate target modeling and discrimination algorithms for a cluster of 10 objects. As a result, Raytheon was selected over Boeing and was awarded the EKV contract. • BV-1 — This was a ground test to certify the procedures that lead to an actual flight test, including all ground and safety checks as well as launch and safety steps. The missile was not launched. • BV-2 — This was a flight test of three-stage Boeing Booster Vehicle with a mass-simulated kill vehicle payload. An anomaly occurred in the first-stage vehicle roll control, but the second- and third-stage motors performed normally. • BV-3 — This flight test resulted in failure when the Boeing Booster Vehicle steered off course 30 seconds after launch and was then ordered to self-destruct off the coast of California. • BV-6 — This was a flight test of the three-stage Orbital Sciences Booster Vehicle with a mass-simulated kill vehicle payload. The launch from Vandenberg Air Force Base proceeded normally over the Pacific Ocean. • BV-5 — This flight test of the Lockheed Martin Booster Vehicle with a mass-simulated kill vehicle payload resulted in failure due to an apparent power drop that prevented the mock EKV from separating from the booster. The flight was delayed by the third-stage rocket motor's circuit boards. • IFT-13B — This was a system-level test of the Orbital Sciences booster carrying a simulated EKV from Kwajalein Atoll against a simulated target from Vandenberg AFB in California. • Medium-range air-launch target — This test featured a C-17 dropping a medium-range target from its rear, 800 mi northwest of the Pacific Missile Range Facility in Hawaii. • CMCM-1A/FT 04-2A — This test was the first of two medium-range target vehicles. • CMCM-1B/FT 04-2B — This test was the second of two medium-range target vehicles. • FT 04-5/FTG 04-5 — This test was an apparent variant of IFT-19 and featured an air-launched long-range target tracked by Cobra Dane radar. • FT-1 — Originally designed as IFT-13A, this test featured an interceptor missile from the Ronald Reagan test site in the Marshall Islands to hit a target from Kodiak, Alaska. The operationally configured warhead and its booster left the ground successfully. • FTX-01/FT 04-1 — Originally designed as IFT-16, then changed to a radar characterization flight test as IFT-16A, then FT 04-1, then FTX-01. This test incorporated radar and targets testing. • CMCM-2B/FTC-02B — This test was a radar certification flight and featured a missile system powered by a two-stage SR-19 rocket flown from the Kauai Test Facility in the Pacific Missile Range Facility. The payload included complex countermeasures, a mock reentry vehicle, and on-board sensor package. • CMCM-2A/FTC-02A — This test repeated FTC-02B to test its radars in the Pacific Missile Range Facility in Hawaii against a target missile that carried countermeasures, a mock warhead, and an on-board sensor package. • FTX-02 — This test of the Sea-Based X-Band Radar revealed "anomalous behavior", and demonstrated a need for software modifications to improve performance. • FTX-03 — This test demonstrated the integration of missile defense sensors to support an interceptor engagement. This revealed the success of the Sea-Based X-Band Radar to be used in future missions. • BVT-01 — A two-stage Ground-Based Interceptor successfully launched from Vandenberg Air Force Base, and after separating from the second-stage booster, the exoatmospheric kill vehicle executed a variety of maneuvers to collect data to further prove its performance in space. All components performed as designed. • GM CTV-01 — The three-stage booster deployed the Exoatmospheric Kill Vehicle to a point in space and executed a variety of pre-planned maneuvers to collect performance data. Initial indications are that all components performed as designed. • GM CTV-02 — A long-range ground-based interceptor was launched from Vandenberg Air Force Base to evaluate performance of alternate divert thrusters for the system's Exoatmospheric Kill Vehicle. The test had planned for the interceptor to fly within a narrow "miss distance" of its target to test the new thrusters' effectiveness. The U.S. military initially stated the test had been a success. But the closest the interceptor came to the target was a distance 20 times greater than what was expected. One of the four thrusters stopped working during the maneuvers, and the interceptor peeled away from its intended course, according to the Pentagon scientists. One of them said the thruster remained inoperable through the final, "homing phase" of the test, when the kill vehicle was supposed to make a close fly-by of the target. MDA acknowledged that a problem surfaced during 28 January exercise: "There was an observation unrelated to the new thruster hardware that has been investigated and successfully root-caused," the agency said in a written response to questions. "Any necessary corrective actions will be taken for the next flight test."

Throughout the program's history, multiple test flights have been canceled, including BV-4, IFT-11, −12, −13, −13A, −15, FTC-03, and, most recently, FTG-04.

The system has a "single shot probability of kill" of its interceptors calculated at 56%, with the claimed total probability of intercepting a single target, if four interceptors are launched, at 97%. Each interceptor costs approximately $75 million. The claim of "97% kill probability" has been dismissed by some experts as a flawed application of basic statistical methods. Said James M. Acton, co-director of the Nuclear Policy Program at the Carnegie Endowment for International Peace, "It assumes that the failure modes of the interceptors are independent of one another. But, in practice, if one interceptor fails because of a design flaw, say, it's much more likely that others will do so too for the same reason."