The problem was first studied during the last year of the Second World War. The only
countermeasure against the V-2 missile that could be devised was a massive barrage of anti-aircraft guns. Even if the missile's trajectory were accurately calculated, the guns would still have a small probability of destroying it before impact with the ground. Also, the shells fired by the guns would have caused more damage than the actual missile when they fell back to the ground. Plans for an operational test began anyway, but the idea was rendered moot when the V-2 launching sites in the Netherlands were captured. In the 1950s and 1960s, missile defense meant defense against strategic (usually nuclear-armed) missiles. The technology mostly centered around detecting offensive launch events and tracking inbound ballistic missiles, but with limited ability to actually defend against the missile. The Soviet Union achieved the first nonnuclear intercept of a ballistic missile warhead by a missile at the
Sary Shagan antiballistic missile defense test range on 4 March 1961. Nicknamed the "Griffon" missile system, it would be installed around Leningrad as a test missiles Throughout the 1950s and 1960s, the United States
Project Nike air defense program focused initially on targeting hostile bombers before shifting focus to targeting ballistic missiles. In the 1950s, the first United States anti-ballistic missile system was the
Nike Hercules, which had the ability to intercept incoming short-range ballistic missiles, but not
intermediate-range ballistic missiles (IRBMs) or ICBMs. This was followed by the
Nike Zeus, which was capable of intercepting ICBMs by using a nuclear warhead, upgraded radar systems, faster computers, and control systems that were more effective in the upper atmosphere. However, it was feared the missile's electronics may be vulnerable to x-rays from a nuclear detonation in space. A program was started to devise methods of hardening weapons from radiation damage. By the early 1960s the Nike Zeus was the first anti-ballistic missile to achieve hit-to-kill (physically colliding with the incoming warhead). In 1963, Secretary of Defense
Robert McNamara diverted funds from the Zeus missile program, and instead directed that funding to the development of the
Nike-X system, which used the high-speed, short-range
Sprint missile. These missiles were meant to intercept incoming warheads after they had descended from space and were only seconds from their targets. To accomplish this, Nike-X required advances in missile design to make the Sprint missile quick enough to intercept incoming warheads in time. The system also included advanced
active electronically scanned array radar systems and a powerful computer complex. During the development of Nike-X, controversy over the effectiveness of anti-ballistic missile systems became more prominent. Critiques of the Nike-X included an estimate that the anti-ballistic missile system could be defeated by Soviets manufacturing more ICBMs, and the cost of those additional ICBMs needed to defeat Nike-X would also cost less than what the United States would spend on implementing Nike-X. Additionally, McNamara reported that a ballistic missile system would save American lives at the cost of approximately $700 per life, compared to a
shelter system that could save lives at a lower cost of approximately $40 per life. As a result of these estimations, McNamara opposed implementation of Nike-X due to the high costs associated with construction and perceived poor cost-effectiveness of the system, and instead expressed support for pursuing arms limitations agreements with the Soviets. After the Chinese government detonated their first hydrogen bomb during
Test No. 6. in 1967, McNamara modified the Nike-X program into a program called
Sentinel. This program's goal was to protect major US cities from a limited ICBM attack, especially on one from China. This would be done by building fifteen sites across the continental US, and one site in each of Alaska and Hawaii. This in turn reduced tensions with the Soviet Union, which retained the offensive capability to overwhelm any US defense. McNamara favored this approach as deploying the Sentinel program was less costly than a fully implemented Nike-X program, and would reduce congressional pressures to implement an ABM system. In the months following the announcements regarding the Sentinel program, Secretary of Defense
Robert McNamara stated: "Let me emphasize—and I cannot do so too strongly—that our decision to go ahead with a limited ABM deployment in no way indicates that we feel an agreement with the Soviet Union on the limitation of strategic nuclear offensive and defensive forces is in any way less urgent or desirable. With the conclusion of the
Cuban Missile Crisis and the withdrawal of Soviet missiles from their strategic positions in Cuba, the USSR started to think about a missile defense systems. A year after the crisis in 1963 the Soviets created the SA-5. Developed by OKB 30, the Russian Special Design Bureau, the effort design to create a monopulse radar started in 1954. The
SALT I talks began in 1969 between the
Nixon administration and the Soviet Union, and led to the
Anti-Ballistic Missile Treaty in 1972. This treaty ultimately limited the US and USSR to one defensive missile site each, with no more than 100
anti-ballistic missiles and their launchers per site. The purpose of the treaty was slow down the nuclear arms race and reduce pressure to build more nuclear weapons. The treaty was intended to be followed by offensive arms limitations. As a result of the treaty and of technical limitations, along with public opposition to nearby nuclear-armed defensive missiles, the US Sentinel program was re-designated the
Safeguard Program, with the new goal of defending US ICBM sites, not cities. The US Safeguard system was planned to be implemented in various sites across the US, including at
Whiteman AFB in Missouri,
Malmstrom AFB in Montana, and
Grand Forks AFB in North Dakota. The Anti-Ballistic Missile Treaty of 1972 placed a limit of two ABM systems within the US, causing the work site in Missouri to be abandoned, and the partially-completed Montana site was abandoned in 1974 after an additional agreement between the US and USSR that limited each country to one ABM system. As a result, the only Safeguard system that was deployed was to defend the
LGM-30 Minuteman ICBMs near Grand Forks, North Dakota. However, it was deactivated in 1976 after being operational for less than four months due to a changing political climate plus concern over limited effectiveness, low strategic value, and high operational cost. In the early 1980s, technology had matured to consider space based missile defense options. Precision hit-to-kill systems more reliable than the early Nike Zeus were thought possible. With these improvements, the
Reagan administration promoted the
Strategic Defense Initiative, an ambitious plan to provide a comprehensive defense against an all-out ICBM attack. In pursuit of that goal, the Strategic Defense Initiative investigated a variety of potential missile-defense systems, which included systems using ground-based missile systems and space-based missile systems, as well as systems using
lasers or
particle beam weapons. This program faced controversy over the feasibility of the projects it pursued, as well as the substantial amount of funding and time required for the research to develop the requisite technology. The Strategic Defense Initiative earned the nickname "Star Wars" due to criticism from Senator
Ted Kennedy in which he described the Strategic Defense Initiative as "reckless Star Wars schemes.". Reagan established the
Strategic Defense Initiative Organization (SDIO) to oversee the development of the program's projects. Upon request by the SDIO, the
American Physical Society (APS) performed a review of the concepts being developed within SDIO and concluded that all of the concepts pursuing use of
Directed Energy Weapons were not feasible solutions for an anti-missile defense system without decades of additional research and development. Following the APS's report in 1986, the SDIO switched focus to a concept called the Strategic Defense System, which would use a system of space-based missiles called
Space Rocks which would intercept incoming ballistic missiles from orbit, and would be supplemented by ground-based missile defense systems. In 1993, the SDIO was closed and the
Ballistic Missile Defense Organization (BMDO) was created, which focuses on ground-based missile defense systems using interceptor missiles. In 2002, BMDO's name was changed to its current title, the
Missile Defense Agency (MDA). See
National Missile Defense for additional details. In the early 1990s, missile defense expanded to include tactical missile defense, as seen in the first
Gulf War. Although not designed from the outset to intercept tactical missiles, upgrades gave the
Patriot system a limited missile defense capability. The effectiveness of the Patriot system in disabling or destroying incoming
Scuds was the subject of congressional hearings and reports in 1992. In the time following the agreement of the 1972
Anti-Ballistic Missile Treaty, it was becoming increasingly more and more difficult for the United States to create a new missile defense strategy without violating the terms of the treaty. During the
Clinton administration, the initial goal the United States had interest in, was to negotiate with the former Soviet Union, which is now
Russia, and hopefully agree to a revision to the treaty signed a few decades prior. In the late 1990s the United States had interest in an idea termed NMD or
National Missile Defense. This idea essentially would allow the United States to increase the number of ballistic missile interceptors that would be available to missile defense personnel at the Alaska location. While the initial ABM treaty was designed primarily to deter the Soviet Union and help create a period of
détente, the United States was primarily fearing other threats such as
Iraq,
North Korea, and
Iran. The
Russian government was not interested in making any sort of modification to the ABM treaty that would allow for technology to be developed that was explicitly banned when the treaty was agreed upon. However, Russia was interested in revising the treaty in such a way that would allow for a more diplomatic approach to potential missile harboring countries. During this period, the United States was also seeking assistance for their ballistic missile defense systems from
Japan. Following the testing of the
Taepo Dong missile by the North Korean government, the Japanese government became more concerned and inclined to accept a partnership for a BMD system with the United States. In late 1998, Japan and the United States agreed to the Naval Wide Theater system which would allow the two sides to design, construct, and test ballistic missile defense systems together. Nearing the end of Clinton's time in office, it had been determined that the NMD program was not as effective as the United States would have liked, and the decision was made to not employ this system while
Clinton served out the rest of his term. The decision on future of the NMD program was going to be given to the next president in line, who ultimately would end up being
George W. Bush. In the late 1990s and early 2000s, the issue of defense against
cruise missiles became more prominent with the new
Bush administration. In 2002, President
George W. Bush withdrew the US from the
Anti-Ballistic Missile Treaty, allowing further development and testing of ABMs under the
Missile Defense Agency, as well as deployment of interceptor vehicles beyond the single site allowed under the treaty. During the Bush's time in office, the potentially threatening countries to the United States included North Korea as well as Iran. While these countries might not have possessed the weaponry that many countries containing missile defense systems had, the Bush administration expected an Iranian missile test within the next ten years. In order to counter the potential risk of North Korean missiles, the
United States Department of Defense desired to create missile defense systems along the west coast of the United States, namely in both
California and
Alaska.
Distant Early Warning Line (DEW) station in western
Greenland is visible in the distance beyond the snow-drifted equipment
pallets in the foreground of this photograph. The DEW Line was designed to track inbound ballistic missiles. There are still technological hurdles to an effective defense against ballistic missile attack. The United States
National Ballistic Missile Defense System has come under scrutiny about its technological feasibility. Intercepting midcourse (rather than launch or reentry stage) ballistic missiles traveling at several miles per second with a "
kinetic kill vehicle" has been characterized as trying to hit a bullet with a bullet. Despite this difficulty, there have been several successful test intercepts and the system was made operational in 2006, while tests and system upgrades continue. Moreover, the warheads or payloads of ballistic missiles can be concealed by a number of different types of decoys. Sensors that track and target warheads aboard the kinetic kill vehicle may have trouble distinguishing the "real" warhead from the decoys, but several tests that have included decoys were successful.
Nira Schwartz's and
Theodore Postol's criticisms about the technical feasibility of these sensors have led to a continuing investigation of research misconduct and fraud at the
Massachusetts Institute of Technology. In February 2007, the US missile defense system consisted of 13 ground-based interceptors (GBIs) at
Fort Greely,
Alaska, plus two interceptors at
Vandenberg Air Force Base, California. The US planned to have 21 interceptor missiles by the end of 2007. The system was initially called
National Missile Defense (NMD), but in 2003 the ground-based component was renamed
Ground-Based Midcourse Defense (GMD). the Missile Defense Agency had 30 operational GBIs, with a total 44 GBIs in the missile fields in 2018. In 2021 an additional 20 GBIs of 64 total were planned, but not yet fielded. They are tasked with meeting more complex threats than those met by the EKV. Defending against
cruise missiles is similar to defending against hostile, low-flying crewed aircraft. As with aircraft defense, countermeasures such as
chaff, flares, and low altitude can complicate targeting and missile interception. High-flying radar aircraft such as
AWACS can often identify low flying threats by using
doppler radar. Another possible method is using specialized satellites to track these targets. By coupling a target's kinetic inputs with
infrared and radar signatures it may be possible to overcome the countermeasures. In March 2008, the
US Congress convened hearings to re-examine the status of missile defense in US military strategy. Upon taking office, President Obama directed a comprehensive review of ballistic missile defense policy and programs. The review's findings related to Europe were announced on 17 September 2009. The Ballistic Missile Defense Review (BMDR) Report was published in February 2010. ==NATO missile defense system==