Missile defense
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 utilizing ground-based missile systems and space-based missile systems, as well as systems utilizing 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 utilize 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 utilizing 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.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). As of 2014, 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: 

Mechanisms: The Conference of National Armaments Directors (CNAD) is the senior NATO committee which acts as the tasking authority for the theater missile defense program. The ALTBMD Program Management Organization, which comprises a steering committee and a program office hosted by the NATO C3 Agency, directs the program and reports to the CNAD.
The focal point for consultation on full-scale missile defense is the Reinforced Executive Working Group. The CNAD is responsible for conducting technical studies and reporting the outcome to the Group.
The NRC Ad hoc Working Group on TMD is the steering body for NATO-Russia cooperation on theater missile defense.
In September 2018, a consortium of 23 NATO nations met to collaborate on the Nimble Titan 18 integrated air and missile defense (IAMD) campaign of experimentation.

Missile defense: By early 2010, NATO will have an initial capability to protect Alliance forces against missile threats and is examining options for protecting territory and populations. This is in response to the proliferation of weapons of mass destruction and their delivery systems, including missiles of all ranges. NATO is conducting three missile defense–related activities:

Active Layered Theater Ballistic Missile Defense System capability: Active Layered Theater Ballistic Missile Defense System is "ALTBMD" for short.