Ground-based Midcourse Defense (GMD) is currently the only U.S. missile defense system devoted to defending the United States from long-range ballistic missile attacks.

GMD and its associated systems span 15 time zones, including interceptors at two locations (Ft. Greely, Alaska and Vandenberg AFB, CA), seven types of sensors on land, sea, and space, and multiple and distributed fire control systems. The GMD system receives cues and tracking information from a variety of space and land-based radars and then intercepts long-range ballistic missiles during their midcourse phase. The 2015 National Defense Authorization Act (NDAA) included funds to conduct environmental reviews of potential East Coast sites for a future addition to the GMD system.

The GMD architecture emerged from the development of the Clinton Administration’s National Missile Defense (NMD) program. The Ballistic Missile Defense Organization (BMDO) formed the initial Joint Program Office for the NMD program in April 1997, with the goal of conducting an integrated test in 1999 and operational deployment by 2003.1 Flight testing of Ground-based interceptors began in 1997, with the first successful intercept in 1999.

Findings from the 1998 Rumsfeld Commission that the United States had underestimated the ballistic missile threat provided impetus for Congress to pass the 1999 National Missile Defense Act, which committed the United States “to deploy as soon as is technologically possible an effective National Missile Defense system capable of defending the territory of the United States against limited ballistic missile attack.”2

The Clinton administration ultimately deferred the decision to deploy homeland missile defense to the next administration.

The December 2001 announcement by the George W. Bush Administration of its decision to withdraw from the ABM Treaty in 2002 opened the door to accelerated investment in a homeland missile defense system, with the aim to deploy an initial limited capability in 2004 or 2005. In 2002, then-Secretary of State Donald Rumsfeld redesignated the BMDO as the Missile Defense Agency (MDA).3 In 2004, Lt. Gen. Henry “Trey” Obering, III, USAF, the Director of MDA, declared limited defensive operations including five GBIs in silos at Fort Greely, Alaska; an upgraded Cobra Dane Radar at Eareckson Air Station in Shemya, Alaska; and an upgraded radar at Fylingdales in the United Kingdom. The GMD system was intended to grow to 44 GBIs distributed between Fort Greely and Vandenberg Air Force Base.4 In addition, the Bush Administration proposed a European GMD site to counter the future development of an Iranian ICBM. This component of the GMD system would have included an additional ten GBIs in Poland and an X-band radar in the Czech Republic.5

In 2009, the Obama Administration announced the cancellation the European GMD sites proposed by the Bush Administration in favor of the European Phased Adaptive

Approach.6 The administration also capped the planned GBI deployments to 30, a reduction from the 44 planned under Bush.7 In 2013, then-Defense Secretary Chuck Hagel announced a reversal of the decision to reduce the U.S. based interceptors and reconstituted a plan to deploy 44 GBIs by 2017.8 In 2015, the administration also awarded a contract to build the S-band Long Range Discrimination Radar (LRDR) at Clear Air Force Station in Alaska to improve the discrimination capability of the radars in the system.9 The FY 2016 NDAA authorized $1.8 billion in funding for the GMD system to improve the CE-II kill vehicle, develop a Redesigned Kill Vehicle (RKV), invest in the LRDR, and support advancements in a selectable two or three stage GBI booster.10


  1. DefenseLINK News, “BMDO Forms New Joint Program Office,” DefenseLINK, April 3, 1997,
  2. “An Act To Declare it to be the Policy of the United States to Deploy a National Missile Defense,” Public Law 106-38, (106) July 22, 1999,
  3. Ibid.
  4. Ibid
  5. Thom Shankar and Nicholas Kulish,  “U.S. and Poland Set Missile Deal,” New York Times, August 14, 2008,
  6. Peter Baker, “White House Scraps Bush’s Approach to Missile Shield,” The New York Times, September 17, 2009,
  7. Jennifer Giffin, “Lawmakers Question Obama’s Missile Defense Cuts,” Fox News, June 16, 2009,
  8. Thom Shanker, David E. Sanger, and Martin Fackler, “U.S. Is Bolstering Missile Defense to Deter North Korea,” The New York Times, March 15, 2013,
  9. Mike Gruss, “Lockheed Martin Lands Missile Defense Radar Contract,” Space News, October 22, 2015,
  10. Thomas Karako, “Missile Defense and Nuclear Deterrence,” in The FY 2016 Budget: The Defense Impact (Washington DC: Center for Strategic and International Studies, February 3, 2015), 14-15,