Ground-Based Midcourse Defense (GMD) is the United States' anti-ballistic missile system for intercepting incoming warheads in space, during the midcourse phase of ballistic trajectory flight. It is a major component of the American missile defense strategy to counter ballistic missiles, including intercontinental ballistic missiles (ICBMs) carrying nuclear, chemical, biological or conventional warheads. The system is deployed in military bases in the states of Alaska and California; in 2018 comprising 44 interceptors and spanning 15 time zones with sensors on land, at sea, and in orbit. In 2019, a missile defense review requested that 20 additional ground-based interceptors be based in Alaska.
GMD is administered by the U.S. Missile Defense Agency (MDA), while the operational control and execution is provided by the U.S. Army, and support functions are provided by the U.S. Air Force. Previously known as National Missile Defense (NMD), the name was changed in 2002 to differentiate it from other U.S. missile defense programs, such as space-based and sea-based intercept programs, or defense targeting the boost phase and reentry flight phases. The program was projected to have cost $40 billion by 2017. That year, the MDA scheduled its first intercept test in three years in the wake of North Korea's accelerated long-range missile testing program.
The system consists of ground-based interceptor missiles and radar which would intercept incoming warheads in space. Boeing Defense, Space & Security is the prime contractor of the program, tasked to oversee and integrate systems from other major defense sub-contractors, such as Computer Sciences Corporation and Raytheon.
The key sub-systems of the GMD system are:
Interceptor sites are at Fort Greely, Alaska and Vandenberg Space Force Base, California. A third site was planned for a proposed US missile defense complex in Poland, but was canceled in September 2009.
In December 2008, the U.S. Missile Defense Agency awarded Boeing a $397.9 million contract to continue development of the program.
In March 2013, the Obama administration announced plans to add 14 interceptors to the current 26 at Fort Greely in response to North Korean threats. The deployment of a second TPY-2 radar to Japan was announced at the same time. While President Obama said that the additional deployment was a hedge against unexpected capabilities, Chinese Ministry of Foreign Affairs spokesman Hong Lei complained that the additional defenses would affect the global strategic balance and strategic trust. In late 2013, there were plans for a proposed Eastern United States missile defense site to house a battery of these missiles.
On 30 April 2014, the Government Accountability Office issued a report stating that the system may not be operational any time soon because "its development was flawed". It said the GBI missile was at that point "capable of intercepting a simple threat in a limited way". On 12 August 2015, Lt. General David L. Mann (commanding general USASMDC/ARSTRAT) characterized GMD as the nation's only ground-based defense against limited ICBM attacks.
Issues with the EKV prompted the MDA to work with Raytheon, Boeing, and Lockheed Martin on a new Redesigned Kill Vehicle (RKV), scheduled to debut in 2025. In 2019, the government issued a stop work order for the RKV after recent test results indicated that the current RKV plan is not viable. The government "initiated an analysis of alternative courses of action"; on 21 August the MDA cancelled the $5.8 billion contract for the RKV. This initiates new work on bids for the successor to the Exo-Atmospheric Kill Vehicle (EKV) to 2025. The current GMD programs continue per plan, with up to 64 GBIs (meaning an additional 20) in the missile fields for 2019.
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 $4,457.8M, an average of $892M per year.
After the FTG-11 test on 25 March 2019, 11 of the 20 (55%) 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.
|IFT-3||2 Oct 1999||Success||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||18 Jan 2000||Failure||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||8 Jul 2000||Failure||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||14 Jul 2001||Success||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||3 Dec 2001||Success||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||15 Mar 2002||Success||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||14 Oct 2002||Success||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||11 Dec 2002||Failure||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||15 Dec 2004||Failure||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||13 Feb 2005||Failure||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||1 Sep 2006||Success||This test involved the first ground-based interceptor launched out of 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||25 May 2007||Failure||With the same setup as FTG-02, the test target flew off-course and an intercept did not occur.|
|FTG-03A||28 Sep 2007||Success||This test was scheduled in response to the failure of FTG-03, this time with a successful intercept.|
|FTG-05||5 Dec 2008||Success||This test launched a threat-representative mock warhead from the Kodiak Launch Complex, Alaska followed by a Ground-Based Interceptor from Vandenberg AFB. All components performed as designed.|
|FTG-06||31 Jan 2010||Failure||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||15 Dec 2010||Failure||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||5 Jul 2013||Failure||This intercept test used an improved CE-I EKV.|
|FTG-06b||22 Jun 2014||Success||This test is designed to demonstrate an intercept and meet the unmet objectives of FTG-06a.|
|FTG-15||30 May 2017||Success||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 March 2019||Success||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.|
|IFT-1A||24 Jun 1997||Success||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||16 Jan 1998||Success||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||28 Apr 2001||Success||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||31 Aug 2001||Success||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||13 Dec 2001||Failure||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||16 Aug 2003||Success||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||9 Jan 2004||Failure||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||26 Jan 2004||Success||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||8 Apr 2005||Success||This test featured a C-17 dropping a medium-range target from its rear, 800 miles (1,300 km) northwest of the Pacific Missile Range Facility in Hawaii.|
|CMCM-1A/FT 04-2A||4 Aug 2005||Success||This test was the first of two medium-range target vehicles.|
|CMCM-1B/FT 04-2B||18 Aug 2005||Success||This test was the second of two medium-range target vehicles.|
|FT 04-5/FTG 04-5||26 Sep 2005||Success||This test was an apparent variant of IFT-19 and featured an air-launched long-range target tracked by Cobra Dane radar.|
|FT-1||13 Dec 2005||Success||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||23 Feb 2006||Success||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||13 Apr 2006||Success||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||28 Apr 2006||Success||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||27 Mar 2007||Mixed||This test of the Sea-Based X-Band Radar revealed "anomalous behavior", and demonstrated a need for software modifications to improve performance.|
|FTX-03||18 Jul 2008||Success||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||6 Jun 2010||Success||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||26 Jan 2013||Success||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||28 Jan 2016||Failure||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."
The system has a "single shot probability of kill" of its interceptors calculated at 56%, with the total probability of intercepting a single target, if four interceptors are launched, at 97%. Each interceptor costs approximately $75 million.
Flight Test Ground-based Interceptor-15, or FTG-15, showcased the system's capabilities, as it was the first successful interception of a simulated intercontinental ballistic missile target by a ground-based interceptor launched by the GMD system.  while the crew was aware there would be a test launch, they were not privy to the exact nature of what they would face and when.