Anti-ballistic missile



An anti-ballistic missile (ABM) is a missile designed to counter ballistic missiles. Ballistic missiles are used to deliver nuclear, chemical, biological or conventional warheads in a ballistic flight trajectory. The term "anti-ballistic missile" describes any antimissile system designed to counter ballistic missiles. However, the term is used more commonly for systems designed to counter intercontinental ballistic missiles (ICBMs).

Current counter-ICBM systems
There are only two systems in the world that can intercept ICBMs. Besides them, many smaller systems exist (tactical ABMs), that generally cannot intercept intercontinental strategic missiles, even if within range—an incoming ICBM simply moves too fast for these systems.

The Russian A-35 anti-ballistic missile system for defense of Moscow, whose development started in 1971. Presently active, it is called A-135 and uses Gorgon and Gazelle missiles with nuclear warheads.

The U.S. Ground-Based Midcourse Defense (GMD; previously known as National Missile Defense – NMD) system has recently reached initial operational capability. Instead of using an explosive charge, it launches a kinetic projectile. The George W. Bush administration accelerated development and deployment of a system proposed in 1998 by the Clinton administration. The system is a dual purpose test and interception facility in Alaska, and in 2006 was operational with a few interceptor missiles. The Alaska site provides more protection against North Korean missiles or launches from Russia or China, but is likely less effective against missiles launched from the Middle East. President Bush referenced the 9/11 attacks and the proliferation of ballistic missiles as reasons for missile defense. The current GMD system has the more limited goal of shielding against a limited attack by a rogue state.

American plans for Central European site
During 1993, a symposium was held by western European nations to discuss potential future ballistic missile defence programs. In the end, the council recommended deployment of early warning and surveillance systems as well as regionally controlled defence systems. During Spring 2006 reports about negotiations between the United States and Poland as well as the Czech Republic were published. The plans propose the installation of a latest generation ABM system with a radar site in the Czech Republic and the launch site in Poland. The system was announced to be aimed against ICBMs from Iran and North Korea. This caused harsh comments by Russia's then-President Vladimir Putin at the Organization for Security and Co-operation in Europe (OSCE) security conference during spring 2007 in Munich. Other European ministers commented that any change of strategic weapons should be negotiated on NATO level and not 'unilaterally' between the U.S. and other states (although most strategic arms reduction treaties were between the Soviet Union and U.S., not NATO). German foreign minister Frank-Walter Steinmeier expressed severe concerns about the way in which the U.S. had conveyed its plans to its European partners and criticised the U.S. administration for not having consulted Russia prior to announcing its endeavours to deploy a new missile defence system in Central Europe. As of July 2007, a majority of Poles were opposed to hosting a component of the system in Poland.

Current tactical systems
Many short-range tactical ABM systems are currently operational, and three are most known: the U.S. Army Patriot, U.S. Navy Aegis combat system, and the Israeli Arrow missile.

United States of America
In several tests, the U.S. military have demonstrated the feasibility of destroying long and short range ballistic missiles. Combat effectiveness of newer systems against 1950s tactical ballistic missiles seems very high, as the Patriot Advanced Capability 3 (PAC-3) had a 100% success rate in Operation Iraqi Freedom.

U.S. Navy Aegis combat system uses RIM-161 Standard missile SM-3.

These systems, as opposed to U.S. GMD system, are not capable of intercepting an ICBM, even if it is in range.

A new system, scheduled for deployment during 2009, is U.S. Terminal High Altitude Area Defense (THAAD) system. It has a longer range, but it is not known if it will be able to intercept ICBMs.

Russian Federation
The Moscow ABM defense system is able to intercept ICBM warheads, and is based on:
 * ABM-1 Galosh (decommissioned)
 * ABM-3 Gazelle
 * ABM-4 Gorgon

Apart from the main Moscow deployment, Russia has striven actively for intrinsic ABM capabilities of its SAM systems.


 * S-300P (SA-10)
 * S-300V (SA-12)
 * S-300PMU-1/2 (SA-20)
 * S-400 (SA-21)
 * S-500 ( In development )

Historical Project 640
Project 640 had been the PRC's indigenous effort to develop ABM capability. The Academy of Anti-Ballistic Missile & Anti-Satellite was established from 1969 for the purpose of developing Project 640. The project was to involve at least three elements, including the necessary sensors and guidance/command systems, the Fan Ji (FJ) missile interceptor, and the XianFeng missile-intercepting cannon. The FJ-1 had completed two successful flight tests during 1979, while the low-altitude interceptor FJ-2 completed some successful flight tests using scaled prototypes. A high altitude FJ-3 interceptor was also proposed. Despite the development of missiles, the programme was slowed down due to financial and political reasons. It was finally closed down during 1980 under a new leadership of Deng Xiaoping as it was seemingly deemed unnecessary after the 1972 Anti-Ballistic Missile Treaty between the Soviet Union and the United States and the closure of the US Safeguard ABM system.

Operational Chinese system
In March 2006, China tested an interceptor system comparable to the U.S. Patriot missiles.

Currently, China has acquired and is license-producing the S-300PMU-2/S-300PMU-1 series of terminal ABM-capable SAMs. China-produced HQ-9 SAM system may possess terminal ABM capabilities. PRC Navy's currently operating modern air-defense destroyers known as the Type 052C Destroyer and Type 051C Destroyer are armed with naval HHQ-9 missiles.

Surface-to-air missiles that supposedly have some terminal ABM capability (as opposed to midcourse capability):
 * HQ-9
 * HQ-19
 * HQ-18
 * HQ-10
 * HQ-16
 * HQ-15

Development of midcourse ABM in China
The technology and experience from the successful anti-satellite test using a ground-launched interceptor during January 2007 was immediately applied to current ABM efforts and development.

China carried out a land-based anti-ballistic missile test on 11 January 2010. The test was exoatmospheric and done in midcourse phase and with a kinetic kill vehicle. China is the second country after US that demonstrated intercepting ballistic missile with a kinetic kill vehicle, the interceptor missile was a SC-19. The sources suggest the system is not operationally deployed as of 2010.

On January 27, 2013, China did another anti ballistic missile test. According to the Chinese Defence Ministry, the missile launch is defensive in character and is not aimed against any countries. Experts hailed China's technological breakthrough because it is difficult to intercept ballistic missiles that have reached the highest point and speed in the middle of their course. Only 2 countries, including the US, have successfully conducted such a test in the past decade.

Rumored midcourse missiles:
 * SC-19
 * KT-1
 * KT-II
 * KT-III

France, United Kingdom and Italy


Italy and France have developed a missile family called Aster (Aster 15 and Aster 30). Aster 30 is capable of ballistic missile defense. On 18 October 2010, France announced a successful tactical ABM test of the Aster 30 missile and on 1 December 2011 a successful interception of a Black Sparrow ballistic target missile. Royal Navy Type 45 destroyers and French Navy and Italian Navy Horizon -class frigates are armed with PAAMS, using Aster 15 and 30 missiles. Also France is developing another version, Aster 30 block II which can destroy ballistic missiles with a maximum range of 3000 km. It will have a Kill Vehicle warhead.

Japan


Since 1998, when North Korea launched a Taepodong-1 missile over northern Japan, the Japanese have been jointly developing a new Surface-to-air interceptor known as the Patriot Advanced Capability 3 (PAC-3) with the US. So far tests have been successful, and there are planned 11 locations that the PAC-3 will be installed. A military spokesman said that tests had been done on two sites, one of them a business park in central Tokyo, and Ichigaya – a site not far from the Imperial Palace. Along with the PAC-3, Japan has installed a US-developed ship-based anti-ballistic missile system, which was tested successfully on 18 December 2007. The missile was launched from a Japanese warship, in partnership with the U.S. Missile Defense Agency and destroyed a mock target launched from the coast.

India


India has an active ABM development effort using indigenously developed and integrated radars, and indigenous missiles. In November 2006, India successfully conducted the PADE (Prithvi Air Defence Exercise) in which an anti-ballistic missile, called the Prithvi Air Defense (PAD), an exoatmospheric (outside the atmosphere) interceptor system, intercepted a Prithvi-II ballistic missile. The PAD missile has the secondary stage of the Prithvi missile and can reach altitude of 80 km. During the test, the target missile was intercepted at a 50 km altitude. India became the fourth nation in the world to acquire such a capability and the third nation to acquire it using in-house research and development. On 6 December 2007, the Advanced Air Defence (AAD) missile system was tested successfully. This missile is an Endoatmospheric interceptor with an altitude of 30 km. According to scientist V K Saraswat of DRDO, the missiles will work in tandem to ensure a hit probability of 99.8 percent.

Arrow
The Arrow project was begun after the U.S. and Israel agreed to co-fund it on 6 May 1986.

The Arrow ABM system was designed and constructed in Israel with financial support by the United States by a multi-billion dollar development program called "Minhelet Homa" with the participation of companies like Israel Military Industries, Tadiran and Israel Aerospace Industries.

During 1998 the Israeli military conducted a successful test of their Arrow missile. Designed to intercept incoming missiles travelling at up to 2 mile/s (3 km/s), the Arrow is expected to perform much better than the Patriot did in the Gulf War. On 29 July 2004 Israel and the United States carried out joint experiment in the USA, in which the Arrow was launched against a real Scud missile. The experiment was a success, as the Arrow destroyed the Scud with a direct hit. During December 2005 the system was deployed successfully in a test against a replicated Shahab-3 missile. This feat was repeated on 11 February 2007.

The Arrow 3 system is presently being developed, and, if successful, will be capable of exo-atmosphere interception of ballistic missiles, including of ICBMs.

Iron dome
Iron Dome (Hebrew: כיפת ברזל) is a mobile air defense system in development by Rafael Advanced Defense Systems designed to intercept short-range rockets and artillery shells. The system was created as a defensive countermeasure to the rocket threat against Israel's civilian population on its northern and southern borders. It is designed to intercept very short-range threats up to 70 kilometers in all-weather situations. It was declared operational and initially deployed on 27 March 2011 near Beersheba. On 7 April 2011, the system successfully intercepted a Grad rocket launched from Gaza for the first time. During the short Gaza War of November 2012, Iron Dome interceptors destroyed 84% of incoming missiles.

David’s sling
David's Sling (Hebrew: קלע דוד), also sometimes called Magic Wand (Hebrew: שרביט קסמים), is an Israel Defense Forces military system being jointly developed by the Israeli defense contractor Rafael Advanced Defense Systems and the American defense contractor Raytheon, designed to intercept medium- to long-range rockets and slower-flying cruise missiles, such as those possessed by Hezbollah, fired at ranges from 40 km to 300 km.

Development in Republic of China (Taiwan)
The Republic of China, commonly known as Taiwan, is also engaged in the development of an anti-ballistic missile system, based on its indigenously developed Tien Kung-II (Sky Bow) SAM system. Although reports suggest a promising system, the ROC government continues to be interested strongly in the American Terminal High Altitude Area Defense (THAAD) program.

1940s and 1950s
The idea of destroying rockets before they can hit their target dates from the first use of modern missiles in warfare, the German V-1 and V-2 program of World War II.

British fighters attempted to destroy V-1 "buzz bombs" in flight prior to impact, with some success, although concentrated barrages of heavy anti-aircraft artillery had greater success. Under the lend-lease program, 200 US 90 mm AA guns with SCR-584 radars and Western Electric/Bell Labs computers were sent to the UK. These demonstrated a 95% success rate against V-1s that flew into their range.

The V-2, the first true ballistic missile, was impossible to destroy in the air. SCR-584's could be used to plot the trajectories of the missiles and provide some warning, but were more useful in backtracking their ballistic trajectory and determining the rough launch locations. The Allies launched Operation Crossbow to find and destroy V-2s before launch, but these operations were largely ineffective. In one instance a Spitfire happened upon a V-2 rising through the trees, and fired on it with no effect. This led to allied efforts to advance over their launching sites in Belgium and the Netherlands.

A wartime study by Bell Labs into the task of shooting down ballistic missiles in flight concluded it was not possible. In order to intercept a missile, one needs to be able to steer the attack onto the missile before it hits. At the speeds the V-2 flew at, this required guns of effectively infinite reaction time, or some sort of weapon with ranges on the order of dozens of miles, neither of which appeared possible. This was, however, just prior to the emergence of high-speed computing systems in the 1950s. By the mid-1950s things had changed considerably, and many forces worldwide were considering ABM systems.

The American armed forces began experimenting with anti-missile missiles soon after World War II, as the extent of German research into rocketry became clear. But defences against Soviet long-range bombers took priority until 1957, when the Soviet Union demonstrated its advances in intercontinental ballistic missile technology with the launch of Sputnik, the Earth's first artificial satellite. The US Army accelerated development of their LIM-49 Nike Zeus system in response. Zeus was subject to criticism throughout its development program, especially from those within the US Air Force and nuclear weapons establishments who suggested it would be much simpler to build more nuclear warheads and guarantee mutually assured destruction. Zeus was eventually cancelled in 1963.

In 1958, a topic of research by the U.S. was the test explosions of several low yield nuclear weapons at very high altitudes over the southern Atlantic ocean, launched from ships. The devices used were the 1.7 kt boosted fission W25 warhead. When such an explosion takes place a burst of X-rays are released that strike the Earth's atmosphere, causing secondary showers of charged particles over an area hundreds of miles across. These can become trapped in the Earth' magnetic field, creating an artificial radiation belt. It was believed that this might be strong enough to damage warheads travelling through the layer. This proved not to be the case, but Argus returned key data about a related effect, the Nuclear electromagnetic pulse (NEMP).

Canada
Other countries were also involved in early ABM research. A more advanced project was at CARDE in Canada, which researched the main problems of ABM systems. A key problem with any radar system is that the signal is in the form of a cone, which spreads with distance from the transmitter. For long-distance interceptions like ABM systems, the inherent inaccuracy of the radar makes an interception difficult. CARDE considered using a terminal guidance system to address the accuracy concerns, and developed several advanced infrared detectors for this role. They also studied a number of missile airframe designs, a new and much more powerful solid rocket fuel, and numerous systems for testing it all. After a series of drastic budget reductions during the late 1950s the research ended. One offshoot of the project was Gerald Bull's system for inexpensive high-speed testing, consisting of missile airframes shot from a sabot round, which would later be the basis of Project HARP. Another was the CRV7 and Black Brant rockets, which used the new solid rocket fuel.

Soviet Union
The Soviet military had requested funding for ABM research as early as 1953, but were only given the go-ahead to begin deployment of such a system on 17 August 1956. Their test system, known simply as System A, was based on the V-1000 missile, which was similar to the early US efforts. The first successful test interception was carried out on 24 November 1960, and the first with a live warhead on 4 March 1961. In this test, a dummy warhead was released by a R-12 ballistic missile launched from the Kapustin Yar, and intercepted by a V-1000 launched from Sary-Shagan. The dummy warhead was destroyed by the impact of 16,000 tungsten-carbide spherical impactors 140 seconds after launch, at an altitude of 25 km.

The V-1000 missile system was nonetheless considered not reliable enough and abandoned in favour of nuclear-armed ABMs. A much larger missile, the Fakel 5V61 (known in the west as Galosh), was developed to carry the larger warhead and carry it much further from the launch site. Further development continued, and the A-35 anti-ballistic missile system, designed to protect Moscow, became operational in 1971. A-35 was designed for exoatmospheric interceptions, and would have been highly susceptible to a well-arrange attack using multiple warheads and radar black-out techniques.

A-35 was upgraded during the 1980s to a two-layer system, the A-135. The Gorgon (SH-11/ABM-4) long-range missile was designed to handle intercepts outside the atmosphere, and the Gazelle (SH-08/ABM-3) short-range missile endoatmospheric intercepts that eluded Gorgon. The A-135 system is considered to be technologically equivalent to the United States Safeguard system of 1975.

American Nike-X of 1960s and plans of Sentinel
Nike Zeus failed to be a credible defence in an era of rapidly increasing ICBM counts due to its ability to attack only one target at a time. Additionally, significant concerns about its ability to successfully intercept warheads in the presence of high-altitude nuclear explosions, including its own, lead to the conclusion that the system would simply be too costly for the very low amount of protection it could provide.

By the time it was cancelled in 1963, potential upgrades had been explored for some time. Among these were radars capable of scanning much greater volumes of space and able to track many warheads and launch several missiles at once. These, however, did not address the problems identified with radar blackouts caused by high-altitude explosions. To address this need, a new missile with extreme performance was designed to attack incoming warheads at much lower altitudes, as low as 20 km. The new project encompassing all of these upgrades was launched as Nike-X.

The main missile was LIM-49 Spartan—a Nike Zeus upgraded for longer range and a much larger 5 megatonne warhead intended to destroy enemy's warheads with a burst of x-rays outside the atmosphere. A second shorter-range missile called Sprint with very high acceleration was added to handle warheads that evaded longer-ranged Spartan. Sprint was a very fast missile (some sources claimed it accelerated to 8,000 mph (13 000 km/h) within 4 seconds of flight—an average acceleration of 90 g) and had a smaller W66 enhanced radiation warhead in the 1–3 kiloton range for in-atmosphere interceptions.

The experimental success of Nike X persuaded the Lyndon B. Johnson administration to propose a thin ABM defense, that could provide almost complete coverage of the United States. In a September 1967 speech, Defense Secretary Robert McNamara referred to it as "Sentinel". McNamara, a private ABM opponent because of cost and feasibility (see cost-exchange ratio), claimed that Sentinel would be directed not against the Soviet Union's missiles (since the USSR had more than enough missiles to overwhelm any American defense), but rather against the potential nuclear threat of the People's Republic of China.

In the meantime a public debate over the merit of ABMs began. Difficulties that had already made an ABM system questionable for defending against an all-out attack. One problem was the Fractional Orbital Bombardment System (FOBS) that would give little warning to the defense. Another problem was high altitude EMP (whether from offensive or defensive nuclear warheads) which could degrade defensive radar systems.

When this proved infeasible for economic reasons, a much smaller deployment using the same systems was proposed, namely Safeguard (described later).

The problem of defense against MIRVs
ABM systems were developed initially to counter single warheads launched from large Intercontinental ballistic missiles (ICBMs). The economics seemed simple enough; since rocket costs increase rapidly with size, the price of the ICBM launching a large warhead should always be greater than the much smaller interceptor missile needed to destroy it. In an arms race the defense would always win.

In practice, the price of the interceptor missile was considerable, due to its sophistication. The system had to be guided all the way to an interception, which demanded guidance and control systems that worked within and outside of the atmosphere. The Nike Zeus was expected to cost about $1 million, about the same as an ICBM. However, due to their relatively short ranges, an ABM missile would be needed to counter an ICBM wherever it might be aimed. That implies that dozens of interceptors are needed for every ICBM. This led to intense debates about the "cost-exchange ratio" between interceptors and warheads.

Conditions changed dramatically in 1970 with the introduction of Multiple independently targetable reentry vehicle (MIRV) warheads. Suddenly each launcher was throwing not one warhead, but several. These would spread out in space, ensuring that a single interceptor would be needed for each warhead. This simply added to the need to have several interceptors for each warhead in order to provide geographical coverage. Now it was clear that an ABM system would always be many times more expensive than the ICBMs they defended against. In summary, the MIRV made ABM economically ineffective, and practically non-workable.

The Anti-Ballistic Missile Treaty of 1972
Technical, economic and political problems described resulted in the ABM treaty of 1972, which restricted the deployment of strategic (not tactical) anti-ballistic missiles.

By the ABM treaty and a 1974 revision, each country was allowed to deploy a mere 100 ABMs to protect a single, small area. The Soviets retained their Moscow defences. The U.S. designated their ICBM sites near Grand Forks Air Force Base, North Dakota, where Safeguard was already under advanced development. The radar systems and anti-ballistic missiles were approximately 90 miles north/northwest of Grand Forks AFB, near Concrete, North Dakota. The missiles were deactivated in 1975. The main radar site (PARCS) is still used as an early warning ICBM radar, facing relative north. It is located at Cavalier Air Force Station, North Dakota.

Brief use of Safeguard in 1975/1976
The U.S. Safeguard system, which utilized the nuclear-tipped LIM-49A Spartan and Sprint missiles, in the short operational period of 1975/1976, was a second counter-ICBMs system in the world. Safeguard protected only the main fields of US ICBMs from attack, theoretically ensuring that an attack could be responded to with a US launch, enforcing the mutually assured destruction principle.

SDI experiments in the 1980s
The Reagan-era Strategic Defense Initiative (often referred to as "Star Wars"), along with research into various energy-beam weaponry, brought new interest in the area of ABM technologies.

SDI was an extremely ambitious program to provide a total shield against a massive Soviet ICBM attack. The initial concept envisioned large sophisticated orbiting laser battle stations, space-based relay mirrors, and nuclear-pumped X-ray laser satellites. Later research indicated that some planned technologies such as X-ray lasers were not feasible with then-current technology. As research continued, SDI evolved through various concepts as designers struggled with the difficulty of such a large complex defense system. SDI remained a research program and was never deployed. Several post-SDI technologies are used by the present Missile Defense Agency (MDA).

Lasers originally developed for the SDI plan are currently in use for astronomical observations. Used to ionize gas in the upper atmosphere, they provide telescope operators with a target to calibrate their instruments.

Tactical ABMs deployed in 1990s
The Israeli Arrow missile system was tested initially during 1990, before the first Gulf War. The Arrow was supported by the United States throughout the 1990s.

The Patriot antiaircraft missile was the first deployed tactical ABM system, although it was not designed from the outset for that task and consequently had limitations. It was used during the 1991 Gulf War to attempt to intercept Iraqi Scud missiles. Post-war analyses show that the Patriot was much less effective than initially thought because of its radar and control system's inability to discriminate warheads from other objects when the Scud missiles broke up during reentry.

Testing ABM technology continued during the 1990s with mixed success. After the Gulf War, improvements were made to several U.S. air defense systems. A new Patriot, PAC-3, was developed and tested—a complete redesign of the PAC-2 deployed during the war, including a totally new missile. The improved guidance, radar and missile performance improves the probability of kill over the earlier PAC-2. During Operation Iraqi Freedom, Patriot PAC-3s had a nearly 100% success rate against Iraqi TBMs fired. However, since no longer range Iraqi Scud missiles were used, PAC-3 effectiveness against those was untested. Patriot was involved in three friendly fire incidents: two incidents of Patriot shootings at coalition aircraft and one of U.S. aircraft shooting at a Patriot battery.

A new version of the Hawk missile was tested during the early to mid-1990s and by the end of 1998 the majority of US Marine Corps Hawk systems were modified to support basic theater anti-ballistic missile capabilities. MIM-23 Hawk missile is not operational in the U.S. service since 2002, but is used by many other countries.

Soon after the Gulf war, the Aegis combat system was expanded to include ABM capabilities. The Standard missile system was also enhanced and tested for ballistic missile interception. During the late 1990s SM-2 block IVA missiles were tested in a theater ballistic missile defense function. Standard Missile 3 (SM-3) systems have also been tested for an ABM role. In 2008 an SM-3 missile launched from a Ticonderoga-class cruiser, the USS Lake Erie, successfully intercepted a non-functioning satellite.

From 1992 to 2000 a demonstration system for the US Army Terminal High Altitude Area Defense was deployed at White Sands Missile Range. Tests were conducted on a regular basis and resulted in early failures, but successful intercepts occurred during 1999.

Brilliant Pebbles concept
Approved for acquisition by the Pentagon during 1991 but never realized, Brilliant Pebbles was a proposed space-based anti-ballistic system that was meant to avoid some of the problems of the earlier SDI concepts. Rather than use sophisticated large laser battle stations and nuclear-pumped X-ray laser satellites, Brilliant Pebbles consisted of a thousand very small, intelligent orbiting satellites with kinetic warheads. The system relied on improvements of computer technology, avoided problems with overly centralized command and control and risky, expensive development of large, complicated space defense satellites. It promised to be much less expensive to develop and have less technical development risk.

The name Brilliant Pebbles comes from the small size of the satellite interceptors and great computational power enabling more autonomous targeting. Rather than rely exclusively on ground-based control, the many small interceptors would cooperatively communicate among themselves and target a large swarm of ICBM warheads in space or in the late boost phase. Development was discontinued later in favor of a limited ground-based defense.

Transformation of SDI into MDA, development of NMD/GMD
While the Reagan era Strategic Defense Initiative was intended to shield against a massive Soviet attack, during the early 1990s, President George H. W. Bush called for a more limited version using rocket-launched interceptors based on the ground at a single site. Such system was developed since 1992, is expected to become operational in 2010 and capable of intercepting small number of incoming ICBMs. First called the National Missile Defense (NMD), since 2002 it was renamed Ground-Based Midcourse Defense (GMD). It was planned to protect all 50 states from a rogue missile attack. The Alaska site provides more protection against North Korean missiles or accidental launches from Russia or China, but is likely less effective against missiles launched from the Middle East. The Alaska interceptors may be augmented later by the naval Aegis Ballistic Missile Defense System, by ground-based missiles in other locations, or by the Boeing Airborne Laser.

During 1998, Defense secretary William Cohen proposed spending an additional $6.6 billion on intercontinental ballistic missile defense programs to build a system to protect against attacks from North Korea or accidental launches from Russia or China.

In terms of organization, during 1993 SDI was reorganized as the Ballistic Missile Defense Organization (BMDO). In 2002 it was renamed to Missile Defense Agency (MDA).

U.S withdrawal from Anti-Ballistic Missile Treaty in 2002
On 13 June 2002, the United States withdrew from the Anti-Ballistic Missile Treaty and subsequently recommenced developing missile defense systems that would have formerly been prohibited by the bilateral treaty. The action was covered by the ostensible reason of needing to defend against the possibility of a missile attack conducted by a rogue state.

The next day, the Russian Federation promptly dropped the START II agreement, intended to completely ban MIRVs.