Ground-based Interceptor (GBI)

Ground Based Interceptor
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The Ground-based Interceptor (GBI) is a component of the Ground-based Midcourse Defense (GMD) System. GBIs are silo-launched and intercept ballistic missiles in their midcourse, while they are outside of the atmosphere and at their highest trajectory. The GBI consists of a multi-stage rocket booster (Boost Vehicle [BV]) and a kinetic kill vehicle (Exoatmospheric Kill Vehicle [EKV]), which makes interception of ballistic missile warheads possible using hit-to-kill technology.

GBI Program History

Predecessors of today’s GBIs, including the Homing Overlay Experiment (HOE) and the Exoatmospheric Reentry Interceptor Subsystem (ERIS), used two stages from a Minuteman I Intercontinental Ballistic Missile (ICBM) fitted with a Kinetic Kill Vehicle (KKV) to form hit-to-kill interceptors. HOE used the first two stages of a Minuteman I as a boost vehicle and deployed an umbrella-like KKV with weights on the ribs of the unfolding kill vehicle to destroy the target missile.1 The ERIS interceptor used the second and third stages of the Minuteman I and a smaller inflatable octagonal “kill enhancer” KKV.2

Clinton Administration 

The GBI program began as the interceptor portion of the National Missile Defense (NMD) architecture developed by the Clinton Administration. The Clinton strategy called for a phased deployment of GBIs that would initially fall under ABM Treaty limits with 100 interceptors deployed at one site at the end of phases one and two. The third and final phase assumed a reworking of the treaty to accommodate a slightly larger deployment of 250 interceptors over two sites in Grand Forks, North Dakota and Fort Greely, Alaska.3 In 1997, the Ballistic Missile Defense Organization (BMDO) formed the initial Joint Program Office for the NMD program with the goal of conducting an integrated test in 1999 and an initial operational deployment in 2003. 4

GBI Launch (Photo: MDA)
GBI Launch (Photo: MDA)

Early tests of the NMD systems used surplus stages of Minuteman missiles as boost vehicles, allowing the first fly-out test to occur in 1997 for the prototype EKV and the first successful intercept test in October 1999.5 Clinton decided to push the decision on deployment of an initial capability of GBIs into the next administration.

Bush Administration 

The direction of GBI deployment was handed off to the George W. Bush administration, which was more dedicated to the deployment of an effective homeland missile defense. In 2002, the Bush administration withdrew from the ABM Treaty, effectively removing any limits on the amount of GBIs and the number of sites they could be deployed at. The Bush plan called for an initial deployment capability by 2004 and the system grew to include 44 GBIs at two sites in the United States, Fort Greely, Alaska and Vandenburg Air Force Base, California, and an additional 10 GBIs at a site in Poland.6

Obama Administration 

In 2009, the newly elected Obama administration announced its intention to reverse the Bush plan to deploy GBI at a site in Poland in favor of a Phased Adaptive Approach.7 They also decided to suspend the procurement of new GBIs at 30, abandoning the goal of 44 interceptors established by the Bush administration. 8 In 2010, the repeated failure in testing of the new CE-II kill vehicle resulted in a reorientation in the GBI program towards an emphasis on testing rather than deployment of new GBIs.9 The reinstitution of the 44 GBI target and a successful flight test of the new EKV in 2013 and then a successful intercept test in 2014 buoyed support for the system.10 Delivery of the 44 interceptors is expected in 2017.11

Booster Development

GBI Booster, Static Test (Photo: MDA)

Initial testing for the GBIs used surplus Minuteman ICBM stages as boosters to facilitate earlier testing of the kill vehicles. The first dedicated booster designed for the GBI program was the Commercial Off-the-Shelf (COTS) booster, which used commercial rocket stages to form a three-stage booster. The first flight test occurred in August 2001, 18 months behind schedule. A December 2001 test of the COTS interceptor resulted in the vehicle veering off course, forcing the destruction of the booster and cessation of testing of the booster.12

In March 2002, the booster program was transferred from Boeing to Lockheed Martin, which developed the BV-plus, an improved version of the COTS booster. In addition, Orbital Sciences Corp. was tasked with creating a competing booster known as the Orbital Booster Vehicle (OBV) which was based on the upper three stages of the commercial Taurus XL launch vehicle. The OBV was successfully tested in February and August 2003 and after delays and the eventual test failure of the BV-plus in 2004, the OBV was selected as the booster for the current GBI.13 In 2010, MDA successfully tested a two-stage version of the OBV booster from Vandenburg Air Force Base.14

In 2016, MDA plans to deploy an upgraded version of the three-stage boost vehicle design to improve reliability and resolve any hardware obsolescence. The project also involves upgrades to the avionics of the booster to provide better flight and booster controllers. MDA is also working on developing a two-stage booster rocket for the GBIs that would incorporate the successful design of the 2010 test and the upgrades of the second phase three-stage boost vehicle. Success in producing a two-stage GBI would allow shorter boost action times, allowing greater flexibility in the location of future deployments.15

Kill Vehicle Development

The Exo-atmospheric Kill Vehicle (EKV) is the GMD’s means of physically destroying incoming target missiles. The EKV consists of a sensor-propulsion package that collides with the re-entry vehicle during the midcourse phase of the missile’s ballistic trajectory, using its own infrared seeker, guidance system, and motor. As it closes in on its target, the EKV integrates data from the X-band radars with its on-board sensors and locks on to the enemy missile. The EKV continuously adjusts its flight path until it collides with the target. The hit-to-kill impact causes complete destruction of the warhead, including any nuclear, chemical, or biological agents.

The Capability Enhancement-I (CE-I), delivered in 2004, became the first deployed EKV for the GMD system.16 The CE-I was produced and delivered until September 2007 with a peak deployment of 24. In all, 33 CE-I kill vehicles were produced and six were expended in tests.17 The accelerated timelines for the initial delivery of the CE-I forced the designs to become a prototype that could demonstrate the viability of hit-to-kill while being deployed quickly. The designers upgraded the connectors to account for obsolescence issues on previous kill vehicles used in tests before the CE-I deployment and have continued to produce a number of subconfigurations to resolve other design and manufacturing issues.18

The second variant of EKV deployed on GBIs is the Capability Enhancement-II (CE-II), which MDA began designing in 2005.19 The CE-II features obsolescence upgrades for computer processors on CE-I that are designed to improve discrimination and a more sensitive infrared seeker. Changes to the algorithm also increased the processor throughput, again intending to enhance the ability of CE-II to discriminate targets from debris and decoys. After two unsuccessful intercept tests in 2010 due to the performance of the CE-II, MDA decided to halt procurement until the issues relating to the failed tests could be resolved. In January 2013, MDA conducted CTV-01, resulting in a successful flight test for the CE-II, followed by a successful intercept test in June 2014.20 Like the CE-I, the CE-II has a number of subconfigurations to resolve design and manufacturing problems encountered through the testing process.

Redesigned Kill Vehicle (RKV)

EKV (Photo: MDA)

The FY2016 NDAA also included funding for the development of new kill vehicle technologies including a Redesigned Kill Vehicle (RKV) and a Multi-Object Kill Vehicle (MOKV). The RKV would include design upgrades for the CE-II to “improve reliability, maintainability, producibility, and affordability,” according to MDA Director VADM James Syring’s 2015 Testimony before the Senate Appropriations Committee.21 The plan is to incorporate enhancements in target acquisition and discrimination and on-demand communication to allow better use of alternative sensor data creating better situational awareness. MDA plans the first flight test of the RKV for 2018 with the first intercept test to follow in 2019.

Multi-Object Kill Vehicle (MOKV)

The MOKV revives the concept of the previously cancelled Multiple Kill Vehicle (MKV), which began in 2004 and was cut by the Obama administration in 2009.22 The system is intended to counter potential salvos of missiles by reducing the number of interceptors required to counter growing missile arsenals. Development of the concepts for the MOKV fall under the Common Kill Vehicle program, which also developed the concepts and requirements for the RKV. Even a successful MOKV program is not likely to produce a deployable interceptor until at least 2030, according to current estimates.

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  1. Andreas Parsch, “Lockheed ERIS,” Directory of U.S. Military Rockets and Missiles, 2003,
  2. Ibid.
  3. Lindsay, James M., and Michael E. O’Hanlon,  Defending America: The Case for Limited National Missile Defense (Washington D.C.: Brookings Institution, 2001).
  4. “BMDO Forms New Joint Program Office,” DefenseLINK, April 3, 1997
  5. James D. Syring, “Homeland Missile Defense,” Presentation to 2014 Space and Missile Defense Conference, Huntsville, AL, August 13, 2014.”
  6. Steve Lambakis, The Future of Homeland Missile Defense (Fairfax, VA: National Institute Press, 2014.)
  7. Peter Baker, “White House Scraps Bush’s Approach to Missile Shield,” New York Times, September 17, 2009,
  8. Jennifer Griffen, “Lawmakers Question Obama’s Missile Defense Cuts,” Fox News, June 16, 2009,
  9. Syring, 2014.
  10. Thom Shanker, David E. Sanger, and Martin Fackler, “U.S. Is Bolstering Missile Defense to Deter North Korea,” New York Times, March 15, 2013,
  11. Syring, 2014.
  12. Andreas Parsch, “Boeing Ground-Based Interceptor (GBI),” Directory of U.S. Military Rockets and Missiles, 2003-2007,
  13. Ibid.
  14. Turner Brinton, “Two-Stage Interceptor Missile Succeeds in First Flight Test,” Space News, June 7, 2010,
  15. Syring, 2014.
  16. Ibid.
  17. “EKVs, RKVs, CKVs, MOKVs and More,” mostlymissiledefense, April 26,2015,
  18. U.S. Inspector General, “Exoatmospheric Kill Vehicle Quality Assurance and Reliability Assessment – Part A,” Report No. DODIG-2014-111, (Alexandria, VA: Department of Defense.)
  19. mostlymissiledefense, 2015.
  20. Syring, 2014.
  21. James D. Syring., “Unclassified Statement of Vice Admiral J.D. Syring, USN Director, Missile Defense Agency Before the Senate Appropriations Committee Subcommittee on Defense,” March 18, 2015,
  22. Mike Gruss, “House Bill Would Revive Dormant Missile Defense Kill Vehicle Project,” Space News, May 11, 2015,
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