National missile defense

missile launch

A payload launch vehicle carrying a prototype exoatmospheric kill vehicle is launched from Meck Island at the Kwajalein Missile Range on December 3, 2001, for an intercept of a ballistic missile target over the central Pacific Ocean.

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National missile defense (NMD) as a generic term is a military strategy and associated systems to shield an entire country against incoming Intercontinental Ballistic Missiles (ICBMs). The missiles could be intercepted by other missiles, or possibly by lasers. They could be intercepted near the launch point (boost phase), during flight through space (mid-course phase), or during atmospheric descent (terminal phase).

The term “National Missile Defense” has several meanings:

  • Most common, but now deprecated: The limited United States ground-based nationwide antimissile system in development since the 1990s. In 2002 this system was renamed to Ground-Based Midcourse Defense (GMD), to differentiate it from other missile defense programs, such as space-based, sea-based, laser, or high-altitude intercept programs. As of 2006, this system is operational with limited capability. It is designed to intercept a small number of nuclear-armed ICBMs in the mid-course phase, using interceptor missiles launched from Alaska. They use non-nuclear kinetic warheads.
  • Current definition: The overall limited U.S. nationwide antimissile program in development since the 1990s. After the renaming in 2002, the term now refers to the entire program, not just the ground-based interceptors and associated facilities. Other elements yet to be integrated into NMD may include sea-based, space-based, laser, and high altitude missile systems. The NMD program is limited in scope and designed to counter a relatively small ICBM attack from a less sophisticated adversary. Unlike the earlier Strategic Defence Initiative program, it is not designed to be a robust shield against a large attack from a technically sophisticated adversary. This article focuses mainly on this system and a brief history of earlier systems which led to it.
  • Any national ICBM defense by any country, past or present. The Russian A-135 anti-ballistic missile system is currently operational around Moscow. It originally used missiles with nuclear warheads to intercept incoming missiles. Some sources indicate some of the missiles may have been later converted to conventional warheads. The U.S. Safeguard ABM system was deployed and briefly operational in 1976, but is currently deactivated. It also used nuclear warheads.
  • Any national missile defense (against any missile type) by any country. Israel currently has a national missile defense against short and medium-range missiles using their Arrow missile system.

The role of defense against nuclear missiles has been a heated military and political topic for several decades.

History of NMD

In the late 1950s, the Nike-Zeus program investigated the use of Nike nuclear missiles as interceptors against Soviet ICBMs. A Nike warhead would be detonated at high altitudes (over 100 km /60 statute miles) above the polar regions in the near vicinity of an incoming Soviet missile. While rocket technology offered some hope of a solution, the problem of how to quickly identify and track incoming missiles proved intractable, especially in light of easily envisioned countermeasures such as decoys and chaff. The Nike-Zeus project was cancelled in 1961.

Project Defender

The Nike-Zeus use of nuclear warheads was necessary given the available missile technology. However, it had significant technical limitations such as blinding defensive radars to subsequent missiles. Also, exploding nuclear warheads over friendly territory (albeit in space) was not ideal. In the 1960s Project Defender and the Ballistic Missile Boost Intercept (BAMBI) concept replaced land-launched Nike missiles with missiles to be launched from satellite platforms orbiting directly above the USSR. Instead of nuclear warheads, the BAMBI missiles would deploy huge wire meshes designed to disable Soviet ICBMs in their early launch phase (the “boost phase”). No solution to the problem of how to protect the proposed satellite platforms against attack was found, however, and the program was cancelled in 1968.

The Sentinel Program

In 1963, U.S. Defense Secretary Robert McNamara announced the Sentinel Program which would have a goal of providing a “thin umbrella” of protection against a limited nuclear strike, such as might be launched by People’s Republic of China. The system consisted of a long range Spartan missile, the short range Sprint missile, and associated radar and computer system. However, U.S. military and political strategists recognized several problems with the system:

  • Deployment of even a limited defensive ABM system might invite a pre-emptive nuclear attack before it could be implemented
  • Deploying ABM systems would likely invite another expensive arms race for defensive systems, in addition to maintaining existing offensive expenditures
  • Then-current technology did not permit a thorough defense against a sophisticated attack
  • Defended coverage area was very limited due to the short range of the missiles used
  • Use of nuclear warheads on antimissile interceptors would degrade capability of defensive radar, thus possibly rendering defense ineffective after the first few intercepts
  • Political and public concern of detonating defensive nuclear warheads over friendly territory
  • An ICBM defense could jeopardize the Mutually Assured Destruction concept, thus being a destabilizing influence

The Safeguard Program

Safeguard was a scaled-down version of Sentinel designed to defend U.S. ICBM sites against attack, rather than protecting cities. Safeguard used the same Spartan and Sprint missiles and the same radar technology as Sentinel. Safeguard solved some problems of Sentinel:

  • Less expensive to develop due to limited geographic coverage and fewer required missiles
  • Avoided public concern of defensive nuclear warheads detonated nearby
  • Provided better intercept probability due to coverage by short range Sprint missile, which was unable to cover the entire defended area under Sentinel.

However Safeguard still retained several of the previously-listed political and military problems.

ABM treaty

These above issues drove the U.S. and USSR to sign the ABM Treaty of 1972. Under the ABM treaty and a 1974 revision, each country was allowed to deploy a single ABM system with only 100 interceptors to protect a single target. The Soviets deployed a system named A-35 using a missile code-named Galosh, designed to protect Moscow. The U.S. deployed Safeguard to defend ballistic missile sites at Grand Forks Air Force Base, North Dakota, in 1975. The U.S. Safeguard system was only briefly operational. The Russian system (now called A-135) has been improved and is still active around Moscow.

Homing Overlay Experiment

Given concerns about the previous programs using nuclear tipped interceptors, in the 1980s the U.S. Army began studies about the feasibility of hit-to-kill vehicles, where an interceptor missile would destroy an incoming ballistic missile just by colliding with it head-on.

The first program, which actually tested a hit-to-kill missile interceptor, was the Army’s HOE (Homing Overlay Experiment) which used a Kinetic Kill Vehicle (KKV) . The KKV was equipped with an infrared seeker, guidance electronics and a propulsion system. Once in space, the KKV could extend a folded structure similar to an umbrella skeleton of 4 m (13 ft) diameter to enhance its effective cross section. This device would destroy the ICBM reentry vehicle on collision. After test failures with the first three flight tests, the fourth and final test on 10 June 1984 was successful, intercepting the Minuteman RV with a closing speed of about 6.1 km/s at an altitude of more than 160 km.

The Strategic Defense Initiative

Main article: Strategic Defense Initiative

On March 23, 1983 President Reagan announced a new national missile defense program formally called the Strategic Defense Initiative but soon nicknamed “Star Wars” by detractors. President Reagan’s stated goal was not just to protect the U.S. and its allies, but to also provide the completed system to the USSR, thus ending the threat of nuclear war for all parties. SDI was technically very ambitious and economically very expensive. It would have included many space-based laser battle stations and nuclear-pumped X-ray laser satellites designed to intercept hostile ICBMs in space, along with very sophisticated command and control systems. Unlike the previous Sentinel program, the goal was to totally defend against a robust, all out nuclear attack by the USSR.

A partisan debate ensued in Congress, with Democrats questioning the feasibility and strategic wisdom of such a program, while Republicans talked about its strategic necessity and provided a number of technical experts who argued that it was in fact feasible (including Manhattan Project physicist Edward Teller). Advocates of SDI prevailed and funding was initiated in fiscal year 1984. The motivation behind this effort largely collapsed with the fall of the Soviet Union and the end of the Cold War.

U.N. Resolution

In December, 1999, the U.N. General Assembly endorsed a resolution aimed at pressing the United States to abandon plans to build an antimissile defense. Voting against the draft, together with the United States, were Albania, Israel and Micronesia. The members of the 15-nation European Union abstained, except for France and Ireland, which voted for the resolution. It calls for continued efforts to strengthen and preserve the 1972 Antiballistic Missile Treaty between the United States and the then Soviet Union, which limits missile defenses. On December 15, 2001, the U.S. withdrew from the ABM treaty.

Current NMD program

The logo of the Missile Defense division of the U.S. National Guard

The logo of the Missile Defense division of the U.S. National Guard

In the 1990s and early 21st century, the stated mission of NMD has changed to the more modest goal of preventing the United States from being subject to nuclear blackmail or nuclear terrorism by a so-called rogue state. The feasibility of this more limited goal remains somewhat controversial. Under President Clinton some testing continued but the project was not given much funding. Some have considered this surprising, in light of Clinton’s supportive remarks on 5 September 2000. He said that “such a system, if it worked properly, could give us an extra dimension of insurance in a world where proliferation has complicated the task of preserving peace.”

The current NMD system consists primarily of ground based interceptor missiles and radar in Alaska which would intercept incoming warheads in space. A limited number of interceptor missiles (about 10) are operational as of 2006. These would possibly be later augmented by mid-course SM-4 interceptors fired from Navy ships and by boost-phase interception by the Boeing YAL-1.

NMD deployment is planned in three phases. The first phase is called Capability 1 (C1), and was originally designed to counter a limited threat from up to about five warheads with either simple or no countermeasures. More recently this phase has been upgraded to include the deployment of up to 100 interceptors and would be aimed at countering tens of warheads. This would require radar upgrades. Since North Korea is perceived to be the earliest missile threat, the interceptors and radar would be deployed in Alaska.

The second phase is called C2 and designed to counter an attack by warheads with more complex countermeasures. It would deploy additional radars and more interceptors, plus a missile-tracking satellite system. The C3 phase is supposed to counter threats consisting of many complex warheads. It would deploy additional radars as well as additional interceptors, including some at a second site, bringing the total to 200 or more. Although the C3 system is the current final deployment goal, the system design permits further expansion and upgrades beyond the C3 level. A Pentagon study concluded that the NMD system could be upgraded by integrating the hundreds of interceptors to be deployed as part of the ship-based Navy Theater Wide missile defense system. These interceptors would be integraded into the sensor infrastructure of the NMD system.

Recent developments

On 14 October 2002, a ground based interceptor launched from the Ronald Reagan Ballistic Missile Defense Site destroyed a mock warhead 225 km above the Pacific. The test included three decoy balloons.

On 16 December 2002 President George W. Bush signed National Security Presidential Directive 23 which outlined a plan to begin deployment of operational ballistic missile defense systems by 2004. The following day the U.S. formally requested from the UK and Denmark use of facilities in Fylingdales, England, and Thule, Greenland, respectively, as a part of the NMD program. The projected cost of the program for the years 2004 to 2009 will be $53 billion, making it the largest single line in The Pentagon’s budget.

Since 2002, the US has been in talks with Poland and other European countries over the possibility of setting up a European base to intercept long-range missiles. A site similar to the US base in Alaska would help protect the US and Europe from missiles fired from the Middle East or North Africa. Poland’s prime minister Kazimierz Marcinkiewicz said in November 2005 he wanted to open up the public debate on whether Poland should host such a base.

In 2002, NMD was changed to Ground-Based Midcourse Defense (GMD), to differentiate it from other missile defense programs, such as space-based, sea-based, and defense targeting the boost phase and the reentry phase.

On 22 July 2004, the first ground-based interceptor was deployed at Ft. Greely, Alaska (63.954° N 145.735° W). By the end of 2004, a total of six had been deployed at Ft. Greely and another two at Vandenberg Air Force Base, California. Two additional were installed at Ft. Greely in 2005. The system will provide “rudimentary” protection.

On 15 December 2004, an interceptor test in the Marshall Islands failed when the launch was aborted due to an “unknown anomaly” in the interceptor, 16 minutes after launch of the target from Kodiak Island, Alaska.

“I don’t think that the goal was ever that we would declare it was operational. I think the goal was that there would be an operational capability by the end of 2004,” Pentagon representative Larry DiRita said on 2005-01-13 at a Pentagon press conference. However, the problem is and was funding “There has been some expectation that there will be some point at which it is operational and not something else these expectations are not uknown, if congress pours more attention and funding to this system, it can be operational relatively quick

On 18 January 2005, the Commander, United States Strategic Command issued direction to establish the Joint Functional Component Command for Integrated Missile Defense. JFCC IMD, once activated, will develop desired characteristics and capabilities for global missile defense operations and support for missile defense.

On 14 February 2005, another interceptor test failed due to a malfunction with the ground support equipment at the test range on Kwajalein Island, not with the interceptor missile itself.

On 24 February 2005, the Missile Defense Agency, testing the Aegis Ballistic Missile Defense System, successfully intercepted a mock enemy missile. This was the first test of an operationally configured Standard missile 3 interceptor and the fifth successful test intercept using this system. On 10 November 2005, the USS Lake Erie detected, tracked, and destroyed a mock two-stage ballistic missile within two minutes of the ballistic missile launch.

On 1 September 2006, the Ground-Based Midcourse Defense System was successfully tested. An interceptor was launched from Vandenberg Air Force Base to hit a target missile launched from Alaska, with ground support provided by a crew at Colorado Springs. This test was described by Missle Defense Agency director Lieutenant General Trey Obering as “about as close as we can come to an end-to-end test of our long-range missile defense system.”

Deployment of the Sea-based X-band Radar system is presently underway.

On 24 February 2007, The Economist reported that the United States ambassador to NATO, Victoria Nuland, had written to her fellow envoys to advise them regarding the various options for missile-defence sites in Europe. She also confirmed that “The United States has also been discussing with the UK further potential contributions to the system.”

In February 2007 US started formal negiotiations with Poland anc Czech Republic concerning construction of missle shield installations in those countries. According to press reports Czech republic agreed to host a missle defence radar on its territory while a base of missle interceptors is supposed to be built in Poland. The Ustka-Wicko base of Polish Army is mentioned as a possible site of US missle interceptors.

July 2003 Report of the American Physical Society

There has been controversy among experts about whether it is technically feasible to build an effective missile defense system. One technical criticism came from U.S. physicists and culminated in the publication of a critical study on the subject by the American Physical Society (APS).

This study focused on the feasibility of intercepting missiles in the boost phase, which the current NMD system does not attempt. The study found it might be possible to develop a limited system capable of destroying a liquid-fuel propelled ICBM during the boost phase. This system could also possibly destroy some solid-propellant missiles from Iran, but not those from North Korea, because of differences in the boost time and range to target. However, there is a trend toward using solid-fueled ICBMs which are harder to intercept during boost phase.

Using orbital launchers to provide a reliable boost-phase defense against solid fuel missiles from Iran or North Korea was found to require at least 1,600 interceptors in orbit. Intercepting liquid-fueled missiles would require 700 interceptors. Using two or more interceptors per target would require many more orbital launchers.

The only boost phase system the U.S. contemplates for near term use is the Airborne laser (ABL). The study found the ABL possibly capable of intercepting missiles if within 300 km for solid fuel missiles or 600 km for liquid fuel missiles, however solid fuel missiles are more resistant to damage.

While the APS report did not address the current U.S. mid-course NMD system, it concluded that were the U.S. in the future to develop a boost-phase ABM defense, there could be significant technical problems limiting effectiveness.

See also the article on anti-ballistic missiles for further discussion on the feasibility of NMD-like systems.


  1. (February 2007) “Missile defence systems Bombs bursting in air“. The Economist (24 February 2007). Retrieved on 27 February 2007. 

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