The Evolution of Homeland Missile Defense

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Note: This appears as Chapter 2 in Missile Defense 2020: Next Steps for Defending the Homeland.

Chapter 2: The Evolution of Homeland Missile Defense

The homeland missile defenses fielded today and those under consideration for the future are shaped by two basic factors: the fundamentals of how missile defense works and past policy and programmatic history.

The fundamentals of ballistic missile defense have changed little over the last 70 years. Concepts for hit-to-kill kinetic intercept (Table 2.1) have been present since the beginning, but early efforts failed in part due to a lack of precision guidance, insufficient or inadequate sensors and computing power, and the problem of discrimination.1

Nuclear kill devices compensated for these early shortcomings in some respects, but challenges remained. Besides numerous adverse effects and limitations, a nuclear weapon–based interceptor still required significant advances in discrimination.

The history of missile defense also reveals the remarkable degree to which historical programs made possible the system in place today. Virtually every element of the architecture and capabilities of today’s Ground-based Midcourse Defense (GMD) system has been conditioned and shaped by decades of history and the legacies of previous programmatic and strategic goals (Table 2.4). The Exoatmospheric Kill Vehicle (EKV) deployed today, for example, in many ways reflects 1990sera technology dating to the National Missile Defense (NMD) effort of the Clinton administration. The EKV in turn represents the product of decades of prior research and development, including the Homing Overlay Experiment (HOE), the Exoatmospheric Reentry-vehicle Interceptor System (ERIS), the High Endoatmospheric Defense Interceptor (HEDI), the Lightweight Exoatmospheric Projectile (LEAP), and Brilliant Pebbles.

DetectionInitial indication by any one of a variety of sensors that a booster has been launched from some point on the surface of the earth, with initial characterization of the booster type.
ClassificationIdentification of the estimated target category based on surveillance, discrimination, and intelligence data.
TrackingThe act of generating and maintaining a time history of an object’s position and any other features of interest.
DiscriminationThe use of surveillance systems to identify lethal reentry vehicles amidst the cloud of debris created by a missile after burnout.
Fire ControlSystems to integrate launch warning, track and discriminate data, manage interceptor launch, provide interceptors with targeting information, and process kill assessment data.
DivertThe ability of the kill vehicle once in space to adjust course based on new information provided by external and onboard sensors.
InterceptThe successful destruction of an incoming missile or reentry vehicle.
Kill AssessmentAn evaluation of information to determine the result of an attempted intercept, for the purpose of providing information for defense effectiveness and reengagements.

While these past efforts made the fielding of GMD possible, they also shaped and constrained it. Today’s system relies not only on technologies but also installations that were not specifically designed for the missile defense mission. In some cases, they are the same facilities. A launch control room used for some early tests of GBIs in the 1990s, for instance, was a holdover from Safeguard days in the 1970s.2

Early Warning Radars designed and built in the 1980s to support nuclear deterrence and the possibility of “launch under attack” have now been pressed into service for missile defense tracking, in addition to serving their traditional role. While necessary to do so, such reliance also brings limitations.


Efforts to defend the U.S. homeland against ballistic missile attack did not begin with the 2002 U.S. withdrawal from the ABM Treaty, nor even in 1983 with President Reagan’s concept of a Strategic Defense Initiative. The first military programs aimed at protecting the United States from ballistic missiles can be traced back to 1946, nine years before the Soviet Union tested the first intercontinental-ranged ballistic missile, the R-7, a version of which also orbited the Sputnik satellite.

Planned Interceptor Levels
Figure 2.1. Planned Interceptor Levels

Indeed, U.S. planners and officials have looked at ways to counter missile threats since they first came into existence. During World War II, allied forces used manned aircraft to tip over V-1s midflight, but also destroyed them on their launchers in Belgium and degraded production facilities within Germany.3

Both left and right of launch attempts to counter missile threats have thus been present from the beginning. As revealed by the Scud hunts during Operation Desert Storm, however, finding and defeating missiles on the ground can be quite challenging.4

The history of homeland missile defense also reveals the trend of high ambition followed by increasing modesty (Table 2.2). This is true for both the scope and nominally planned deployments of homeland missile defense. Early missile defense programs under the auspices of the Nike program were once on course for wide coverage of the United States against a Soviet nuclear attack. This was eventually reduced to merely providing force protection of the U.S. ICBM fields under the Safeguard system. The ABM Treaty of 1972 permitted both the United States and the Soviet Union two missile defense sites each, one for the National Capital Region and one for an ICBM field, but in 1974 was amended to permit only a single site.

SentinelProtect cities from a small Chinese arsenal or Nth country
SafeguardDefend ICBMs from USSR attack
SDI Phase 1Counterforce mission to interfere with timing and offensive operations of Soviet ICBM force
Later SDIPrevention of military attack by the Soviet Union
GPALSDefend against third world powers or accidental launches from a major nuclear power, 10 to 200 reentry vehicles
Clinton IOCIntercept five ballistic missiles
Clinton C1Intercept 10 ballistic missiles
Clinton C2Intercept 10 ballistic missiles with limited countermeasures
Clinton C3Intercept up to 20 ballistic missiles with more advanced countermeasures
Bush-Obama GMDIntercept undefined number of ballistic missiles from both North Korea and Iran

The pattern of increased modesty is again repeated with the planned deployments of ground-based kinetic interceptors. During Phase 1 of the Strategic Defense Initiative, for instance, some 1,000 GBIs were identified as a supplement to an additional architecture of one (or several) thousand space-based interceptors. This number was revised down to 750 GBIs with the Global Protection Against Limited Strikes (GPALS) program under the George H. W. Bush administration.

The Clinton administration developed a three-phase NMD architecture that envisioned first 20, then 100, and then 250 GBIs deployed at several sites. The Clinton Capability-3 architecture included a robust satellite architecture and numerous X-band radars colocated at the sites for the Cold War–era early warning radars.5

In terms of size and scope, even the Clinton C2 was more ambitious than both the GMD architecture deployed today and that now envisioned for the 2020 time frame (Figure 2.1).


With the damage inflicted by Germany’s V-2 ballistic missiles during World War II, efforts to defend the U.S. homeland against missile attack became a high postwar priority for U.S. defense planners. In May 1946, the U.S. Army Equipment Board, under the leadership of Army General Richard Stillwell, issued a report identifying postwar requirements for U.S. ground forces. The report predicted the appearance of guided intercontinental missiles carrying nuclear weapons, as well as the inability of existing fighter aircraft or anti-aircraft defenses to defeat them. It also envisaged the need for “guided interceptor missiles, dispatched in accordance with electronically computed data obtained from radar detection stations.”6

The Stillwell report recommended that “defensive measures against atomic weapons should be accorded priority over all other National Defense projects.”7

The report led to the U.S. Army Air Force’s Project Wizard and Project Thumper programs to develop missile intercept capability. The nascent state of radar technology, however, presented serious hurdles for early warning and tracking of incoming threats. Both programs were later abandoned, but research conducted for Project Thumper contributed to the U.S. Air Force CIM-10 BOMARC surface-to-air missile, in service from 1959 to 1972 to defend North America against bomber attack.

In 1957, the maiden launch of the Soviet Union’s R-7 Semyorka ICBM and the orbiting of Sputnik both reinvigorated America’s sense of urgency for ballistic missile defense. That same year, the President’s Science Advisory Committee issued the influential Gaither report, one of the earliest articulations of the strategic purpose of active defense for both military retaliatory assets and population centers:

The main protection of our civil population against a Soviet nuclear attack has been and will continue to be the deterrent power of our armed forces, to whose strengthening and securing we have accorded the highest relative value. But this is not sufficient unless it is coupled with measures to reduce the extreme vulnerability of our people and our cities. As long as the U.S. population is wide open to Soviet attack, both the Russians and our allies may believe that we shall feel increasing reluctance to employ [Strategic Air Command] in any circumstance other than when the United States is directly attacked.8

In addition to recommending the active defense of Strategic Air Command (SAC) bases against ballistic missile attack, the commission also concluded that “an effective air defense is so important to ensure continuity of government, and to protect our civil population, our enormously valuable civil property and military installations, that these development programs we suggest should be pushed with all possible speed.”9

Nike Ajax, Hercules, and Zeus Interceptors
Figure 2.2. Nike Ajax, Hercules, and Zeus Interceptors From front to back: Nike Zeus, Nike Hercules, Nike Ajax interceptors. Source: U.S. Space and Missile Defense Command.

The committee identified two categories of systems that could provide some defense against ballistic missile attack. These included adaptations of existing “off the shelf” weapons such as the nuclear-tipped Nike Hercules anti-aircraft missile. With some modifications, the Gaither report surmised, these systems could provide a preliminary, lower tier defense of SAC installations and the basis for later evolution. The committee warned against the use of nuclear-tipped interceptors at lower altitudes for defense of population centers and recommended research into higher altitude interceptors that would reach into midcourse, while acknowledging that “to do this in the face of decoys poses a number of technical questions, the answers for which require a high priority research and test program.”10


Early inter-service rivalries in the new missile age of the Cold War soon led to a basic division of labor for the missile defense problem. With the Navy preoccupied with SLBMs and the Air Force with ICBMs and bombers, the U.S. Army took the lead on ABM or missile defense efforts. By 1955, two years prior to the release of the Gaither report, the Army had commissioned the Nike-II study to examine the feasibility and requirements for a higher altitude homeland missile defense. Many of the key findings would still be recognized by today’s missile defense engineers, such as the need for “local radars in the vicinity of the target and forward radars for initial detection.”11

The Nike-II study also identified discrimination between warheads and decoys as a particularly difficult challenge, recommending a point-defense system capable of intercepting warheads in their terminal phase after decoys and other debris had been dispersed. Another important finding was the need for consistent tracking and accurately guided interceptors. Even with a nuclear warhead, the acceptable miss-distances were small, and increasing the yield of the warhead did not significantly enlarge the interceptor’s kill radius.12

Throughout Nike’s development, numerous other studies were conducted, largely under the auspices of the Advanced Research Program Agency (ARPA) formed in 1958. Noteworthy projects included Project BAMBI (an acronym for Ballistic Missile Boost Intercept) and an Air Force program funded by ARPA examining the potential for satellite-based defenses. The BAMBI concept involved interceptors launched over Soviet territory from 30-ton, low-earth orbit satellites to interrupt a Soviet ICBM’s propulsion during boost phase.13

The ARPAT (ARPA-terminal) program considered the next generation of terminal phase interceptors beyond Nike. Project GLIPAR (Guide Line Identification Program for Antimissile Research) explored the viability of more exotic technologies, including various forms of directed energy. GLIPAR concluded, however, that such efforts were not “within the bounds of existing scientific knowledge.”14

The first test “intercept” of an ICBM by the Army-led Nike-Zeus missile program took place in 1962. Although the test did not involve a nuclear detonation, developers deemed it to have flown close enough to the target that a nuclear detonation would have destroyed the reentry vehicle. Despite the system’s initial success, it was not deployed due to cost, concerns with detonating a nuclear weapon in the atmosphere, and its limited operational capability.15

Particular technical concerns included the slow speed of the Nike-Zeus booster and the limited capabilities of the system’s manually swiveled radars.

Using a nuclear warhead to destroy incoming missiles in space helped overcome the lack of precision guidance, thanks to neutron heating. As President John F. Kennedy’s science adviser, Jerome Wiesner, explained, “When one explodes a nuclear weapon near another, a flux of neutrons is released; these penetrate into the guts of the second nuclear weapon and heat it enough to melt it.” This destruction of adversary nuclear weapons from the inside was critical to success in space intercepts, as an ABM nuclear explosion would not create destructive shockwaves in the vacuum of space. “However,” Wiesner noted, “this effect does not work over very great distances . . . so the Nike nuclear explosion could be effective against only a limited number of incoming targets.”16

Starfish Prime High Atmospheric Nuclear Test, 1962
Figure 2.3. Starfish Prime High Atmospheric Nuclear Test, 1962. A belt of ionized gas caused by the 1962 Starfish Prime nuclear test (1.45 megaton). Source: Wikimedia.

Another complication facing Nike-Zeus was the phenomenon known as “blackout,” in which a nuclear explosion in the upper atmosphere would cause air molecules to ionize. Wiesner again explained: “For a while the gas acts like a metal . . . so that radar waves cannot go through it and you cannot see what is behind it.”17 This limited the utility of the ground radars and made them susceptible to deliberate blinding. Both redundancy and hardening were important for sensors as well as other components. The “blackout” effect was observed during the 1962 “Starfish Prime” high-altitude nuclear tests.18

The Kennedy administration expressed concern over these limitations, as well as with concerns over cost. Secretary of Defense Robert S. McNamara’s “whiz kids” concluded in 1963 that the cost of missile defense was greater than the cost to the Soviets to build more missiles. McNamara asserted that the Soviets would respond to an ABM system by increasing the size of their nuclear arsenal, accomplishing only an increase in both sides’ defense spending.19

In the wake of the Cuban Missile Crisis, however, President Kennedy placed a higher priority on Project Defender and Nike. In January 1963, the Nike-X was created to shore up the weaknesses of Zeus. Nike-X relied on faster Sprint interceptors located around areas likely to be targeted by ICBMs to intercept warheads reentering the atmosphere. Nike-X also employed improved radar elements, including integration of a forward-based acquisition radars, together with separate radars for tracking and discrimination.


Secretary McNamara, now with the Lyndon Johnson administration, continued his push to limit ABM deployments. Toward the end of 1966, however, the administration faced increasing pressure from Congress to deploy an ABM system amid widespread reports of Soviet ABM deployments. In response, President Johnson requested money for fiscal year 1968 to deploy Nike-X. The administration, however, decided to delay Nike-X pending attempts to spark Soviet interest in a treaty limiting ABM deployments.

The proposed Nike-X interceptor, now dubbed Sentinel, would minimize congressional pressure on the administration to develop a large-scale system. McNamara settled on a limited ABM system that could protect the United States from the much smaller Chinese nuclear threat or an accidental Soviet launch. The proposed deployments instead garnered opposition, however, from people living in protected areas, from scientists who thought the system was too dangerous to station them near populated areas, and from members of Congress that preferred to tailor the system for the Soviet threat.20

Further concern came from those worried that defenses would undermine arms control negotiations or contribute to an arms race.21

In 1969, the administration of President Richard Nixon suspended Sentinel and announced plans to restructure it as a new program called Safeguard, a more limited deployment of the Nike-X system to protect only ICBM fields against a counterforce strike. In addition to concern over new Soviet missile technologies, Nixon may have also viewed the retention of some ABM capabilities as a useful bargaining chip in future arms control negotiations.22

Besides Sprint, Safeguard also deployed an updated Nike-Zeus interceptor renamed Spartan, capable of intercept outside the atmosphere. The combination of the two represented an early iteration of a “layered” defense. Despite improvements, the basic shortcomings of nuclear-based intercept continued to haunt the program. Kinetic intercept seemed far off, but the way appeared to be paved. Simulations run by the Army Advanced Ballistic Missile Defense Agency (ABMDA) in 1969, for instance, seemed to indicate that the combination of optical homing with ground-based radars might make hit-to-kill possible.23

Signing of the ABM Treaty, 1972
Figure 2.4. Signing of the ABM Treaty, 1972. Source: U.S. State Department.

Efforts to limit ABM technology in favor of retaliation-based deterrence culminated with the 1972 signing and ratification of the ABM Treaty between the United States and Soviet Union. The treaty imposed legal limits on the development and deployment of missile defense systems, pursuant to the promise that “effective measures to limit antiballistic missile systems would be a substantial factor in curbing the race in strategic offensive arms and would lead to a decrease in the risk of outbreak of war involving nuclear weapons.”24

The restrictions placed on ABM development were quite comprehensive and have had lasting implications for U.S. missile defense up to the present day. Specifically, the treaty limited the United States and USSR to two missile defense sites (later reduced to one), with no more than 150-kilometer radius separating the interceptors and radars.25 Within this radius, deployment was limited to 100 fixed, land-based interceptors. Supporting ABM radars had to be colocated within the designated ABM site and were also limited in number. The testing and development of interceptors was also limited to fixed, silo-based launchers, precluding mobile defenses or basing at sea, in the air, or in space.26

Although technically permitted by the ABM Treaty and deployed for a short time, the Safeguard system was soon scuttled. The deployment was confined to the Michelson Safeguard Complex at Grand Forks, North Dakota. Congress subsequently voted to deactivate the site in 1975, however, and the site was closed in February 1976, just 315 days after achieving its initial operational capability.27

Research into missile defense technologies continued under the treaty, but at a much scaled-down level. In part, such efforts hedged against Soviet breakout and the increase in the number of warheads required to carry out a counterforce strike against U.S. ICBM fields.28

As a defensive accompaniment to the MX missile program in 1979, for instance, the Army proposed the development of the Low Altitude Defense (LoAD) missile defense system. Approximately half the size of a Sprint, LoAD would use a nuclear payload to destroy incoming warheads lower in the atmosphere—below 50,000 feet. As such, it would have been only suitable to defend alreadyhardened targets, such as ICBM silos.29

LoAD was canceled in 1983, five months prior to the first flight test of the MX Peacekeeper ICBM.


When President Reagan announced the Strategic Defense Initiative in 1983, it came with the hope of rendering nuclear weapons “impotent and obsolete.” The initiative was heralded by many as “an unprecedented development in recent U.S. strategic policy.”30

President Reagan Delivers Speech on SDI, March 23, 1983
Figure 2.5. President Reagan Delivers Speech on SDI, March 23, 1983

Others, including ABM Treaty architects, mobilized to again prosecute their case against defenses and in favor of mutual vulnerability.31

The context of the SDI announcement, however, was growing concern about increasing Soviet SS-18 ICBM deployments as a “direct challenge to our policy of deterrence based on assured retaliation”—namely, what appeared to be the growing vulnerability of U.S. ICBMs and bombers to a Soviet first strike.32 Most of the speech that announced SDI was in fact devoted to the Soviet ICBM advances.

The SDI Phase I architecture had the express purpose of complicating Soviet offensive options and thereby closing the perceived “window of vulnerability” to a counterforce attack. Richard Cheney, then secretary of defense, described its purpose to be intercepting 40 percent of the first wave of Soviet missiles and 50 percent of all SS-18s.33

The concept for a Phase II was to enhance deterrence by denying the USSR the ability to destroy “militarily significant portions of important sets of targets (such as missile silos or command and control nodes) in the United States.” The stated goal of Phase III was to maintain Phase II’s level of protection in the face of advancing Soviet countermeasures while aspiring to “even higher levels of protection,” perhaps assured survival of the U.S. population despite full-scale nuclear war. Directed energy would be key to achieve this goal, but it was recognized that “it is unlikely that confidence in [directed energy] feasibility could be established by the early 1990s.”34

Between the Safeguard era and the early 1980s, several technological advances had emerged that would play a significant role in making hit-to-kill more technologically feasible. These included increases in computing speed, signal processing and imaging, miniaturization of electronic circuitry, and investments in the precision guidance revolution during the 1970s.

SDI’s notional architecture included a wide range of terrestrial and space-based systems.35 Although directed energy weapon research was a featured component of SDI research, its lack of technological maturity excluded it from the proposed components for what became three periods for SDI: Phase 1, a somewhat more modest “Phase 1 Modified,” and finally Brilliant Pebbles. A look at its architecture reveals a network of sensors, interceptors, and command and control that in some ways was the precursor of the missile defense architecture of today.

Phase 1 included hundreds of space-based interceptor carrier satellites (SBIs), along with 1,000 ground-based interceptors and a layered system of sensors.36

The space-based sensor layer consisted of the Boost Surveillance and Tracking System (BSTS), which would have detected missiles at launch, and the Space-based Surveillance and Tracking System (SSTS), low-earth orbit satellites for tracking and discrimination.37

Additional discrimination capability was to be provided by the Ground-based Surveillance and Tracking System (GSTS), a nonorbital pop-up type sensor based on a ground-based rocket. In the event of a major attack, a GSTS could be fired aloft (remaining on station for 600 to 1,200 seconds) and help with midcourse tracking, thereby supplementing space-based sensors that might be blinded or disabled. GSTS pop-up sensors were envisioned at each of three sites within the United States, with 12 per site.38 Yet another layer of sensors included ground-based radars.39

Approved by the Defense Acquisition Board on July 30, 1987, Phase 1 included both SBIs and ground-based interceptors to defeat missiles both in and outside of the atmosphere. A subsequent and more modest Phase 1 Modified plan reduced the number of ground-based HEDI and ERIS interceptors and switched from garages of 10 SBIs to more distributed singlets.

Strategic Defense Initiative Phase 1 Concepts
Figure 2.6. Strategic Defense Initiative Phase 1 Concepts

While the SDI architecture was of course never realized, its components were tailored to perennial missile defense problems of detection, tracking, and discrimination and, at the conceptual level, may provide lessons for future efforts. Many of the ideas for current and future improvements to today’s BMDS find at least an analogue to some element of SDI concepts.

Homing Overlay Experiment

During the 1970s, interest in overcoming the problems associated with nuclear interceptors led to early experiments into kinetic kill technologies—interceptors that would physically collide with an incoming warhead and destroy it with the force of impact. In prior decades, hit-to-kill had been viewed as beyond state-of-the-art, but progress made in the fields of infrared sensing and computers began moving it into the realm of the possible.40

The U.S. Army undertook these early efforts, which led to the Homing Overlay Experiment (HOE) Task Force in 1977. These efforts ran in parallel to the precision strike revolution begun in the 1970s as part of the Carter administration’s “offset” strategy.

Homing Overlay Experiment Interceptor
Figure 2.7. Homing Overlay Experiment Interceptor. Source: Wikimedia.

The HOE used a modified Minuteman booster to deliver a kill vehicle in the path of an incoming reentry vehicle (RV). Once separated from the booster, the 247 kilogram (kg) kill vehicle (KV) extended a 13-foot “radial net” of metallic spokes resembling a bicycle wheel to increase the chances of striking the RV. Fueled, the HOE may have weighed around 1,200 kg.41 Similar “kill enhancement” mechanisms would continue to return in future programs, including early kill vehicles for the GBIs launched on Minuteman ICBM boosters in the late 1990s.42

Guided primarily by onboard infrared sensors, the HOE collided head-on with its target. With revitalized interest in missile defense following President Reagan’s announcement of the Strategic Defense Initiative in 1983, HOE pushed past the concept phase and entered testing.

HOE experienced three intercept failures in 1983 due to malfunctions in the KV’s infrared and guidance systems. In June 1984, HOE scored a successful intercept of a dummy warhead 100 miles above the earth’s surface, the first exoatmospheric hit-to-kill intercept of a ballistic missile. This success was somewhat mired in controversy, with reports citing allegations that the test had been rigged by placing a beacon in the dummy warhead.43

In 1994, a congressional investigation debunked these allegations, but nevertheless stated that “steps were taken to make it easier for the interceptor’s [infrared] sensor to find the target” by having it heated prior to launch.44

The General Accounting Office (GAO; later renamed the Government Accountability Office), described these steps as a “reasonable decision for this early technology demonstration.”45

In 1993, DoD acknowledged there had been an ongoing “deception plan” associated with HOE to influence arms control negotiations and Soviet military spending. The GAO concluded that the deception program had been discontinued prior to the fourth HOE test and that it did not affect the results of the intercept. As an operational system, however, the Army determined HOE itself to be too heavy and too expensive to deploy.46


Following the HOE intercept, in 1984 the BMD Systems Command (BMDSCOM) allocated funds for its further development under a program called the High Endoatmospheric Defense Interceptor (HEDI), as well as allocating $2 million to prove the concept for the Exoatmospheric Reentry Interceptor Subsystem (ERIS).47

The purpose of ERIS was to further develop the technology to engage reentry vehicles outside the earth’s atmosphere and, more specifically, to increase hit-to-kill probability, reduce cost, and develop a seeker that could lie dormant for long periods of time and require little maintenance.48

The kill vehicle weighed about 200 kg.49

On January 28, 1991, the first ERIS test was conducted from the Kwajalein Missile Test Range to intercept a Minuteman missile from Vandenberg AFB.50

The goals for the test were to communicate target information to the ERIS interceptor during flight, acquire the proper target, and maneuver toward the target and destroy it. The test achieved all of its major goals and resulted in an intercept, representing another important hit-to-kill milestone. It did not involve discrimination, but that was not a goal of the test.51 Whereas the 1984 HOE experiment “exploited 1978 technologies,” the 1991 ERIS kill vehicle was “based on 1986 technology,” in both cases a development lag of about five years.52

The second ERIS test was less successful. On March 13, 1992, an ERIS was launched from the same test range to accomplish the same goals as the previous test, with the addition of using its infrared sensor to properly discriminate between two objects based on their respective temperatures.53

While the additional sensing goal was achieved, the ERIS kill vehicle failed to intercept the target.54

Funded concurrently with the ERIS, the HEDI program looked to develop technology for a ground-launched endoatmospheric component of a layered defense architecture.55

HEDI interceptors were to defeat missiles at the end of their midcourse and into the terminal phase of flight. While no intercepts were attempted, HEDI technology contributed to what is now known as the Terminal High Altitude Area Defense (THAAD) system.


The Lightweight Exoatmospheric Projectile (LEAP) was initially conceived in the 1980s by the Army’s Strategic Defense Command to be a hit-to-kill projectile small enough to be launched from a rail gun.56

The rail gun effort was discontinued, but the program migrated to BMDO and the U.S. Navy, evolving into an effort to further miniaturize kinetic kill vehicle technology. The prototype LEAP kill vehicle was fitted with an infrared sensor system, a dense electronics package, and a more compact set of divert thrusters.

In June 1991, LEAP successfully completed a free flight hover test at Edwards Air Force Base, highlighting its initial capacity to be integrated onto missile systems. In 1993, the program was transferred to the Navy. Through 1995, four test flights took place under Navy command, in which LEAP completed 42 of the 43 objectives.57

This success allowed for LEAP to be deemed operationally fit to be adapted for the Navy’s Theater Ballistic Missile Defense Program for exoatmospheric missile defense.58

As such, LEAP is the technological forbearer of the Aegis Standard Missile-3, but also laid the groundwork, particularly in miniaturization, for today’s EKV.59

Space-based Interceptors

The Strategic Defense Initiative was perhaps best known, however, for its layer of orbiting kill vehicles. SDI’s Phase 1 concept included a number of satellites serving as SBI “garages,” housing 10 hit-to-kill interceptors apiece.60

Concerns about the relative vulnerability of these garages to anti-satellite (ASAT) weapons, however, led to a more distributed design known as Brilliant Pebbles, a constellation of smaller, independent kill vehicles in space that would have presented a more dispersed target set for ASATs to defeat.61

Alternative Proposals

One alternative proposal to SDI from Congress was the Accidental Launch Protection System (ALPS), forwarded by Senator Sam Nunn in 1988. The ALPS concept challenged Phase 1 by proposing a combination of nearer-term deployments and longer-term research in directed energy. To remain ABM Treaty compliant, ALPS would have employed only 70 ERIS and 30 HEDI interceptors at Grand Forks—the same number and location of Safeguard, but with two kinetic kill interceptors rather than the nuclear-armed Spartan and Sprint. This capacity might have provided protection against only one or two MIRV-equipped Soviet ICBMs, however, and would have been of little use against an SLBM launch. In 1990, the Senate voted down an amendment to fund ALPS from SDI funds.62

Another alternative came after the Soviet coup attempt in August 1991, when three senators, including William Cohen, introduced a bill for the deployment of 700 to 1,200 ground-based interceptors at five to seven sites across the continental United States—a sort of nonnuclear version of Sentinel.63


The fall of the Soviet Union and relaxation of the strategic threat environment led the George H. W. Bush administration and some members of Congress to scale back, but not cancel, the Strategic Defense Initiative and focus on more limited threats.

In 1990, soon to be director of the Strategic Defense Initiative Organization (SDIO), Ambassador Henry Cooper, wrote a report suggesting the redirection of SDI Phase 1 into something more modest, in light of the reduced threats from formerly Soviet missiles. Cooper recommended that SDI be scaled back to deal with limited attacks of up to 200 warheads, the number that might be expected from a rogue submarine, and to rely primarily on presently available technologies.64 In emphasizing accidental or rogue launches it resembled ALPS, but was expanded or redirected to include missile threats from additional countries.

Over the next year, this concept evolved again and became known as Global Protection Against Limited Strikes (GPALS). In his 1991 State of the Union address, President Bush called for SDI to be “refocused” to provide protection from limited ballistic missile strikes, “whatever their source.”65 Instead of enhancing deterrence by complicating a Soviet first strike, however, it was expressly “protection” focused, in the event deterrence failed: “With GPALS, we are talking about protection against limited strikes, rather than deterrence of a massive attack.” Whereas some previous concepts focused on the continental United States, GPALS was billed as a 50-state solution, including Alaska and Hawaii.66

GPALS included a mix of space- and surface-based sensors, and interceptors based in space and on land or at sea. The 1,000 space-based interceptors were devoted to intercepting any missile with a range in excess of 600 to 800 kilometers, and the ground-based interceptors and other defenses in the United States or deployed abroad were to intercept missiles of almost any range.67

The new feature came with the space layer—namely, Brilliant Pebbles (BP). The BP concept (Figure 2.8) consisted of kinetic kill vehicles housed individually in a carrier vehicle called a “life jacket,” to provide each pebble with communications, power, and protection from particulate space debris. BPs were designed to engage incoming missiles in the boost or early midcourse phase, reducing the burden on but not replacing ground-based interceptors.

Each pebble would also have had an onboard seeker, computing capability, and communication, allowing it to be less reliant on external sensors as well as communicate to other BPs and the ground.68 The kill vehicles themselves were not so dissimilar from ground-based kill vehicles, such as those designed for ERIS or today’s EKV, except that they were pre-accelerated and parked in orbit.

In 1989, BP underwent a series of major reviews for technological feasibility, which ultimately found the concept to be within the bounds of available technology, although additional steps were recommended to make BPs less vulnerable to attack. By 1990, BP was cleared for demonstration and validation.69

Brilliant Pebbles Concept
Figure 2.8. Brilliant Pebbles Concept. Source: Missile Defense Agency.

The ground-based layer remained necessary for both shorter-range missile attacks abroad and as an underlay for the United States. For the newly “increased priority on theater missile defense programs,” PATRIOT evolution, the new THAAD program, the jointly developed Arrow, and ship-based interceptors were under consideration. For homeland defense, the plan was to have a competition between the Exo-Endoatmospheric Interceptor (E2I) and the (strictly exoatmospheric) Ground-based Interceptor (GBI). Between these two, and therefore between the midcourse and terminal missions, SDIO director Ambassador Cooper noted, “Which interceptor we would lead with would depend on whether we’re better at working the discrimination problem or the atmospheric heating problem.”70

The GPALS rollout emphasized the commonality between space-based and ground-based kill vehicles development. Both did a similar job, regardless of where they began from or whether their acceleration is done on warning or in advance. Cooper emphasized that:

[T]he technology that they are now exploiting in the ground-based interceptor is a direct derivative of the space-based interceptor work that was going on previous to Brilliant Pebbles. So what we are seeing is a convergence of the technology to be exploited by interceptors, based on the ground or based in space, to conduct intercepts in space. The ground-based interceptor does its thing in space. So the issue is, where do you put it when it’s not actually being energized. Is it to be based on the ground or is it to be based in orbit? In my mind, there are technical issues as to which costs less, what’s more effective, which is more intrusive on the environment in terms of basing issues—and there are questions, political issues, raised by those who have concerns about so-called weapons in space, and so on.71

GPALS also deemphasized directed energy weapons for being beyond the state-of-the-art and expanded the mission of Brilliant Pebbles to include not only boost-phase but also early midcourse intercept. To address midcourse discrimination, GPALS coupled Brilliant Pebbles with a satellite constellation known as Brilliant Eyes, composed of small infrared sensors in low-earth orbit.72 As with subsequent National Missile Defense proposals, its deployment would have violated the ABM Treaty without renegotiation. Cooper predicted that if development efforts went well and the decision was made to deploy, treaty issues would come to a head by the end of the 1990s.73

The 1991 National Missile Defense Act

The Gulf War further enhanced interest in missile defense. An Army program, the PATRIOT antiaircraft missile (originally begun under Secretary Robert S. McNamara in 1965), was pressed into missile defense duty. Reports suggest that the Iraqis fired 42 Scuds at Israel and another 46 at Saudi Arabia and other Gulf states.74 In one such attack, in February 1991, an Iraqi Scud missile struck a U.S. Army barracks in Saudi Arabia, killing 27 U.S. military personnel and wounding 98 others.75

Although the U.S. military initially believed that PATRIOTs had intercepted many Iraqi Scuds, they may instead have merely broken up on reentry, perhaps due to faulty modifications to extend their range.76

Following the conflict, Congress passed the Missile Defense Act of 1991, which called for the deployment of “an anti-ballistic missile system, including one or an adequate additional number of anti-ballistic missile sites and space-based sensors, capable of providing a highly effective defense of the United States against limited attacks of ballistic missiles.”77 It also called for “highly effective theater missile defenses” to protect forward-deployed forces and allies.

The act called for an initial deployment by 1996 of 100 fixed interceptors at a single site, designed to protect the United States against “limited ballistic missile threats, including accidental or unauthorized launches or Third World attacks.” The window would have required, then, about five years from enactment to deployment. This first deployment was also to include ground-based battle management radars and optimized use of space sensors for launch detection and interceptor cueing.

This scale of 100 interceptors was intended to be ABM Treaty–compliant, but the 1991 act encouraged negotiations to amend the ABM Treaty to permit the construction of additional interceptor sites, greater use of space assets for battle management, and clarifications to permit greater flexibility in missile defense research and testing.78 The act also called for continued research into Brilliant Pebbles, but excluded it, by name, from the prescribed architecture.


The Clinton administration initially pivoted away from homeland defense. The homeland defense budget was slashed by more than half, from over $2 billion to under $1 billion.79

The Strategic Defense Initiative Organization (SDIO) was restructured and renamed the Ballistic Missile Defense Organization (BMDO), with a new programmatic and budgetary focus on theater or short-range defenses.80 This shift included the cancellation of Brilliant Pebbles, marked by Secretary of Defense Les Aspin’s declaration that he was “taking the stars out of Star Wars.”81

The emphasis on national efforts would remain on “developing” but not “deploying.”82

When Republicans took control of Congress in early 1995, national missile defense again became a point of contention. Later that year, President Clinton vetoed the initial submission of the FY 1996 defense authorization act, specifically because of its mandate to deploy by 2003 a national missile defense capable of defending all 50 states.83

In his veto message, Clinton noted that such a mandate would “likely require a multiple-site architecture that cannot be accommodated within the terms of the existing ABM Treaty.”84

The veto also cited the conclusions of a National Intelligence Estimate (NIE) in 1995, which predicted that “no country, other than the major declared nuclear powers, will develop or otherwise acquire a ballistic missile in the next 15 years that could threaten the contiguous 48 states and Canada.”85 The apparent exclusion of Alaska and Hawaii would be the basis for much concern.

Congress rejected the conclusions and seized upon the caveats of the 1995 NIE and, in response, created the bipartisan Commission to Assess the Ballistic Missile Threat to the United States, more commonly known as the Rumsfeld Commission after its chair, Donald Rumsfeld. The commission’s report concluded that the 1995 NIE had underestimated the future threat of ballistic missiles to the United States, most notably by underestimating the prospects for foreign assistance from Russia and China. The report concluded that both Iran and Iraq could deploy an ICBM within 10 years of a decision to begin a program and that North Korea was likely close to developing a missile capable of hitting western parts of the United States.86 The report also cautioned that the United States might have little warning of foreign missile development and that new proliferators may be willing to operationally deploy missiles without significant flight testing.

Shortly after the report’s release, North Korea tested a three-stage variant of its Taepodong-1 missile, overflying Japan in what appeared to be an attempt at satellite orbit.87

The development further energized the national missile defense debate and helped spur passage of the National Missile Defense Act of 1999. The act declared it U.S. policy “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.”88 A revised NIE was released in September 1999, stating that “during the next 15 years the United States most likely will face ICBM threats from Russia, China, and North Korea, probably from Iran, and possibly from Iraq . . .”89

In this context, the Clinton administration began to put together plans for a National Missile Defense (NMD). In some ways it resembled a scaled-down version of the GBI component from GPALS (minus the space-based layer) or perhaps ALPS. The details of NMD development are especially important for understanding the capabilities and limitations of GMD today (Table 2.3).

PhaseC1Expanded C1C2C3
MissionIntercept 5 targets without countermeasuresIntercept 10 ICBMs with limited countermeasuresIntercept 10 ICBMs with less-limited countermeasuresIntercept up to 20 ICBMs
GBI SitesAlaskaAlaskaAlaskaAlaska, North Dakota
UEWRs Beale, Clear, Cape Cod, Flyingdales, ThuleBeale, Clear, Cape Cod, Flyingdales, ThuleBeale, Clear, Cape Cod, Flyingdales, Thule, South Korea
X-band Radars ShemyaShemya, Clear, Flyingdales, ThuleShemya, Clear, Flyingdales, Thule, Beale, Cape Cod, Grand Forks, Hawaii, South Korea
In-Flight Comm. Systems Central Alaska, Caribou, ShemyaCentral Alaska, Caribou, Shemya, MunsingCentral Alaska, Caribou, Shemya, Munsing, Hawaii
SBIRS-High 455
SBIRS-Low 62424

By 1996, the Clinton administration elected to pursue a “3+3” strategy for development of a national missile defense, which would include a three-year period of testing and development followed by three years to deploy an initial system, if it was deemed technologically feasible.90 The timing of the plan was intentionally “phased” to both ensure effectiveness of the system and to allow time to renegotiate the ABM Treaty. The first phase, tailored to a “threshold” threat, was called Capability-1 (C1). The C1 configuration included 20 interceptors at one site, in either Alaska or North Dakota, capable of intercepting a few simple warheads with no countermeasures.91

This site could be deployed by 2003 and then built up by 2005 to around 100 interceptors (the ABM Treaty–compliant number).92

President Clinton later emphasized to Russian president Vladimir Putin the seriousness of the American effort: “Don’t make the mistake of thinking that this is just about current politics or me protecting Al Gore. This is a real strategic problem for the United States.”93

Eventually a decision was made to deploy the first site in Alaska to provide limited coverage even to the far reaches of Alaska and Hawaii. North Dakota would have given better coverage of the continental United States, but it would have left certain parts of Hawaii and Alaska undefended, and amending the ABM Treaty requirement for radar colocation and radar direction may have seemed easier than amending it to permit more than one interceptor site.94

The C1 configuration would also include building an X-band radar in Shemya, Alaska, and upgrading various existing early warning radars to provide sensor coverage. Alaska was not the optimal location for a robust defense of the continental United States, but it did satisfy the political criteria for 50-state coverage, even if the character of that coverage for much of the continental United States was weakened as a result, most notably for the East Coast. Then U.S. deputy secretary of defense John Hamre later remarked, “We have . . . done modeling that shows that there are very good reasons why you may want to put it [an X-band radar] in Alaska. . . . Now, if it goes to Alaska, that requires us to sit down and make a change in the treaty.”95

The C2 configuration kept the number of interceptors at 100, but upgraded them. It also called for three more X-band radars, a space-based infrared sensor constellation (SBIRS-low) to improve initial tracking, and upgraded command, control, and communications, all with a 2010 goal of intercepting missiles with more advanced countermeasures. The final C3 deployment would expand the number of interceptors to 250 evenly distributed between Alaska and North Dakota sites and nine X-band radars deployed on U.S. and allied territory.96

During the Deployment Readiness Review (DRR) phase (1996–1998) and the Deployment Decision Review (DDR) phase (1998–2000), BMDO began some early tests of a prototype kill vehicle, derived in part from the LEAP and other early hit-to-kill experiments. Several competitors produced designs for what became known as the EKV, as well as for the booster underneath it. To facilitate early testing of the EKV, early tests of the NMD systems used surplus stages of Minuteman missiles as boost vehicles, as had earlier tests. These early steps allowed the first fly-out test of a prototype EKV in 1997. The first successful EKV intercept occurred in October 1999—just 15 years after HOE and eight years after ERIS.97

Secretary of Defense William Cohen was a supporter of swiftly fielding a ballistic missile defense. Within the administration, however, some felt that the goal of 2003 was too ambitious, and a 1998 review of the testing program led by General Larry Welch warned against a “rush to failure.”98

Cohen agreed but was hesitant to push deployment back until 2007, as suggested by the Pentagon’s Office of Program Analysis and Evaluation. Splitting the difference, he decided on the middle point of a 2005 deployment date.99

Yet another element of homeland missile defense present in the Clinton era plans is that of using ship-based radars and potentially also ship-based interceptors. In 2000, the chief of naval operations, Admiral Jay Johnson, proposed to the secretary of defense that ships could make the then-proposed NMD more effective, assisting with midcourse and potentially also boost-phase defense. A similar proposal had been made years before by SDIO Director Cooper.100

In addition, the Clinton administration sought to engage Russia in what became known as the “demarcation talks,” intended to establish a clearer demarcation between national missile defense and theater missile defense systems that would clarify the ABM Treaty’s restrictions on certain systems. An agreement to this effect was reached with Russia in 1997.101

At minimum, the Clinton administration’s architecture would have required at least amendment and perhaps the radical redrafting of the ABM Treaty in order to permit more than one GBI site and the construction of the X-band radar at Shemya, Alaska. Indeed, by the late years of the Clinton administration, lawyers were consulted to determine whether some level of initial construction at Shemya would be permissible under the treaty, such as the pouring of concrete for the foundation.102

Consistent with the administration’s previous “3+3” timeline, the schedule for a decision to deploy a national missile defense was set for late 2000. The results of the initial two tests were mixed, with a successful intercept in October 1999 and a failure in January 2000. The decision would not be made until after the third test, which would take place on July 8, 2000. The test was unsuccessful: the clamshell cover protecting the kill vehicle’s eyes did not eject and never separated from the second stage. An avionics processor, hardly cutting-edge technology, was later deemed to have been the cause.103

In September 2000, President Clinton decided to defer the deployment decision to his successor.104

The speech announcing the deferment decision also laid out the rationale for continued efforts, however, especially in light of the failure of applying Cold War deterrence to new threats:

The question is, can deterrence protect us against all those who might wish us harm in the future? Can we make America even more secure? The effort to answer these questions is the impetus behind the search for NMD. The issue is whether we can do more, not to meet today’s threat, but to meet tomorrow’s threat to our security.

For example, there is the possibility that a hostile state with nuclear weapons and long-range missiles may simply disintegrate, with command over missiles falling into unstable hands; or that in a moment of desperation, such a country might miscalculate, believing it could use nuclear weapons to intimidate us from defending our vital interests, or from coming to the aid of our allies, or others who are defenseless and clearly in need. . . .

Now, no one suggests that NMD would ever substitute for diplomacy or for deterrence. But 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 the peace. Therefore, I believe we have an obligation to determine the feasibility, the effectiveness, and the impact of a national missile defense on the overall security of the United States.105

While the Clinton administration did not deploy any components of national missile defense, it nevertheless began the development and laid out the basic elements for what would soon be renamed Ground-based Midcourse Defense (GMD).


The George W. Bush administration wasted little time in moving forward on national missile defense, largely along the lines laid out in the previous years. Rather than amend the ABM Treaty to accommodate national missile defense efforts, the president in December 2001 announced plans to withdraw from the treaty pursuant to its terms, citing its diminished relevance in a world where the threat of Soviet attack had been superseded by missile threats from multiple and less predictable actors. Due to the requirement for a six-month notice of withdrawal, the treaty would not officially terminate until June 13, 2002.

George W. Bush ABM Withdrawal Announcement, December 13, 2001
Figure 2.9. George W. Bush ABM Withdrawal Announcement, December 13, 2001. Source: Getty Images / Alex Wong.

In announcing the U.S. intention to withdraw, the president emphasized the changing strategic environment and the relation of missile defense to deterrence:

Today, I have given formal notice to Russia, in accordance with the treaty, that the United States of America is withdrawing from this almost 30-year-old treaty. I have concluded the ABM Treaty hinders our government’s ability to develop ways to protect our people from future terrorist or rogue-state missile attacks.

The 1972 ABM Treaty was signed by the United States and the Soviet Union at a much different time, in a vastly different world. One of the signatories, the Soviet Union, no longer exists. And neither does the hostility that once led both our countries to keep thousands of nuclear weapons on hair-trigger alert, pointed at each other. The grim theory was that neither side would launch a nuclear attack because it knew the other would respond, thereby destroying both.

Today, as the events of September the 11th made all too clear, the greatest threats to both our countries come not from each other, or other big powers in the world, but from terrorists who strike without warning, or rogue states who seek weapons of mass destruction.

We know that the terrorists, and some of those who support them, seek the ability to deliver death and destruction to our doorstep via missile. And we must have the freedom and the flexibility to develop effective defenses against those attacks. Defending the American people is my highest priority as Commander in Chief, and I cannot and will not allow the United States to remain in a treaty that prevents us from developing effective defenses.106

While waiting for withdrawal to take effect, Secretary of Defense Rumsfeld issued a January 2002 memo creating the Missile Defense Agency (MDA) and granting it special acquisition authorities in recognition of the “special nature of missile defense development, operations, and support.”107 The memo mandated streamlined executive oversight and reporting requirements for MDA to facilitate quick deployment of an initial operating capacity. In June 2002, the treaty withdrawal took effect and work began at Fort Greely, Alaska. After having reviewed a wide array of concepts, those left over from the Clinton administration were regarded as the most mature and formed the basis of the path forward. The Nuclear Posture Review of 2001 described the path forward as having two dimensions: first, the need to acquire rudimentary “near-term emergency capabilities” for 2003 to 2006, and “operational capabilities” from 2006 to 2008.108

On December 16, 2002, President Bush issued National Security Presidential Directive 23 (NSPD-23), which declared it the policy of the United States to “develop and deploy, at the earliest possible date, ballistic missile defenses drawing on the best technologies available,” a slight reformulation of the NMD Act of 1999.109

NSPD-23 also eliminated the distinction between national and theater missile defenses, a rejection of the previous treaty demarcation agreements from 1997, since the distinction depended as much on context as on physics. One person’s theater defense was another’s national missile defense. European commentators praised the move. NATO Secretary General Lord Robertson praised the move for its reception abroad, saying that “taking the ‘N’ out of ‘NMD’ has changed perceptions on that and encouraged a more rational debate.”110

NSPD-23 further directed the Department of Defense to deploy an initial capability to defend the homeland by the end of fiscal year 2004. This capability was envisioned as a first step toward the future deployment of more robust “evolutionary” missile defenses that could include space-based interceptors and other capabilities previously banned by treaty. NSPD-23 focused the U.S. missile defense effort on defending against missiles “of varying ranges in all phases of flight,” an injunction that in time would make it into the charter of the Missile Defense Agency.111

In support of this policy, the Bush administration also initiated several rounds of diplomacy with U.S. allies to explain the withdrawal and to explore possible avenues of missile defense cooperation. The administration also reassured Russia that the treaty decision was not intended to threaten Russia’s strategic nuclear capabilities, and despite initial objections, President Vladimir Putin acknowledged that the U.S. withdrawal “does not pose a threat to the national security of the Russian Federation.”[112. About the ABM Treaty, Putin stated,

“As is known, Russia, like the United States and unlike other nuclear powers, has long possessed an effective system to overcome antimissile defense. So, I can say with full confidence that the decision made by the President of the United States does not pose a threat to the national security of the Russian Federation.”

Ministry of Foreign Affairs of the Russian Federation, “Statement Made by Russian President Vladimir Putin on December 13, 2001, regarding the Decision of the Administration of the United States of America to Withdraw from the Antiballistic Missile Treaty of 1972,” December 14, 2001.] The United States and Russia also engaged in a series of bilateral discussions on possible missile defense cooperation, in accordance with the Joint Declaration signed by Presidents Bush and Putin in May 2002, but did not conclude with any meaningful agreement.112

To facilitate the rapid deployment of an initial system, MDA was granted significant flexibility to construct facilities and procure and field assets. The development process was dubbed “capabilities-based” acquisition, the logic of which was explained by then MDA director Lieutenant General Ronald Kadish:

Missile defense has perhaps more uncertainties in this regard than many other mission areas. We do not want to alter our baseline every time we recognize a change in the threat. Such changes could ripple through the program and likely cause significant delay and cost. So instead of a point threat, we are setting a wider range of boundaries for adversarial capabilities over time in defining our own needed capabilities. The baseline we set must be able to deal with surprises and changes in the threat. A capability-based approach allows us to adjust to those changes in ways that the traditional requirement-based approach does not.113

Such flexibility was arguably necessary, given NSPD-23’s directive that there would be no “final, fixed missile defense architecture,” that the initial deployments would evolve with the threat and technological change, and with “the number and location of systems” changing over time.114

GBI Fleet Evolution, 2004-2016
Figure 2.10. GBI Fleet Evolution, 2004-2016

In September 2004, then MDA director Lieutenant General Trey Obering declared “limited defensive operations” status for GMD. At the time, this capability was quite limited indeed, consisting of only five GBIs at Fort Greely, Alaska, and the upgraded Cobra Dane radar at Eareckson Air Station in Shemya, Alaska.115

Aegis BMD ships then in the Sea of Japan were tethered to the GMD system for testing, but were yet to be operationally integrated.

Other elements soon came online. Over the next four years, additional interceptors continued to be emplaced, rising to 24 by the end of 2008. In 2006, the newly constructed Sea-based X-band radar (SBX-1) arrived in the Pacific to enhance the GMD system’s discrimination capabilities, participating in its first GMD intercept in September of that year. The TPY-2 and SPY-1D radars were operationally integrated through the Command and Control, Battle Management, and Communications (C2BMC) program, and the Early Warning Radar at Thule also received upgrades to contribute to the missile defense mission.

The Bush administration also continued or began longer-term technology development programs to lay the groundwork for subsequent generations of missile defense technology. These included the Multiple Kill Vehicle (MKV), the Kinetic Energy Interceptor (KEI), and the Airborne Laser (ABL), a technology demonstrator to validate the use of aerial directed energy platforms for boost-phase intercept.

As with NMD, GMD was largely but not exclusively oriented westward, weighted toward the North Korean threat. In 2007, President Bush proposed deploying additional GMD system elements in Europe designed to intercept a potential Iranian ICBM headed toward the United States. The location of 10 GBIs in Poland and an X-band radar in the Czech Republic would have also allowed this system to provide some limited protection for European NATO allies from the developing Iranian IRBM arsenal, but additional interceptors for NATO territorial defense would still have been needed.116 Those 10 GBIs would have been in addition to the 44 intended for Fort Greely and Vandenberg and would thus have brought the total number of homeland defense interceptors to 54. The decision to put interceptors on European soil created significant Russian opposition, despite the limited nature of the deployment and its inability to affect Moscow’s strategic arsenal.117

Because they were located closer to Iran than those in Alaska were to North Korea, the GBIs intended for Europe would have had to intercept an Iranian ICBM relatively earlier in its flight, during the ascent component of the midcourse phase. For this reason, the European third site was intended to host two-stage rather than three-stage boosters.118 From the outside, the two-stage GBI configuration was virtually indistinguishable from the three-stage configuration in Alaska, but without the additional weight and required burn time of the third stage. This allowed for a quicker deployment of the kill vehicle. Agreements were signed with both Poland and the Czech Republic to accommodate these sites.119 Deployments of GBIs in Poland were scheduled to begin in 2011, with completion scheduled for 2013.


President Barack Obama made a number of significant decisions affecting the scope and nature of homeland missile defense, most notably to cancel plans to deploy the full number of 44 GBIs divided between Alaska and California, scale back (and ultimately cancel) the ABL, and terminate the MKV program, which would have developed multiple kill vehicles for each GBI, simplifying the discrimination problem and improving shot doctrine.120 The KEI program was also canceled, which would have used a highly energetic booster to intercept missiles in the ascent phase.121

Homeland and Regional Modernization, 1996-2021
Figure 2.11. Homeland and Regional Modernization, 1996-2021. Note: Modernization herein includes appropriations for procurement and for RDT&E. The “homeland” category includes GMD/NMD and related programs: SBX, LRDR, MKV/MOKV, Improved Homeland Defense Interceptors, and Midcourse Defense Test. The “regional” category includes THAAD, Aegis, and PATRIOT/MEADS.

In September 2009, President Obama also announced a major shift in European missile defense. The plans for a GBI site in Poland and X-band radar in Czech Republic were to be scrapped. In its place would go a new architecture, dubbed the European Phased Adaptive Approach (EPAA).122 The Clinton administration had explicitly deemphasized strategic or national missile defense in favor of theater missile defense, and the Obama administration again put new emphasis on regional missile defenses, with corresponding budget movements (Figure 2.3).

The first three phases of the EPAA would include sea- and later land-based SM-3s, the latter concept having previously originated during talks to identify a midcourse intercept solution for Israel.123 EPAA also had a fourth phase featuring an as-yet designed SM-3 IIB interceptor much smaller than a GBI or KEI that, from Europe, would theoretically be able to intercept intercontinental-range missiles.124

In February 2010, the administration released its Ballistic Missile Defense Review (BMDR), which set as its first priority “to defend the homeland against the threat of limited ballistic missile attack.” It emphasized maintaining the nearly 30 GBIs that had already been emplaced while also completing Missile Field 2 at Fort Greely “as a hedge against the possibility that additional deployments become necessary.”125 The new policy review also reiterated the shift against GBIs in Europe and toward developing the SM-3 IIB.126

The notional SM-3 IIB was characterized as requiring burnout velocities of around 5.5 kilometers per second.127

Subsequent studies revealed a number of difficulties with implementing the concept.128 To achieve the necessary speed, the SM-3 IIB might have had to expand the diameter of the interceptor from 21 to 27 inches, which in turn would require a modification to the U.S. Navy’s Mark 41 Vertical Launching System (VLS) to accommodate added width.129

The SM-3 IIB concept also envisioned a throttleable solid motor, a new technology the development of which would have proved challenging for the administration’s timeline.

The proposed deployment in Romania and Poland also was perhaps not the optimal location, given the slower velocity of an SM-3 IIB relative to a GBI. GAO concluded that while the Poland site could be effective with operational changes to launch interceptors during boost phase, a sea-based deployment would be more effective and would not require changes to firing doctrine.130 Deployment on Aegis ships would have required either changing the proposed liquid propulsion system, or reversing a ban on liquid propellant systems on ships. Should an expanded VLS not have been possible, it may even have required deck mounting, a concept pursued as well for the previous KEI.

Given the long development time anticipated with the SM-3 IIB, the Obama administration announced another programmatic shift in March 2013. Just weeks after a February 2013 nuclear test by North Korea, Secretary of Defense Chuck Hagel announced the cancellation of the EPAA’s fourth phase.131

This effectively killed the SM-3 IIB and eliminated the coupling of homeland defense with European deployments. Hagel also announced that the administration would reverse its previous decision to forgo deployment of an additional 14 GBIs to Alaska, bringing the number back to 44.132

Following this announcement, the Department of Defense submitted to Congress its Homeland Defense Hedging Policy and Strategy in June 2013. While describing a range of planned and potential activities, the report noted “risks to the nation associated with having too few deployed GBIs,” and that “future ICBM threats from North Korea or Iran could increase in complexity, which could require a greater expenditure of interceptors to achieve an acceptable probability of engagement success.”133

The report provided greater details on the shifts announced by Secretary Hagel in March, as well as a number of other steps the Obama administration would take to improve U.S. homeland missile defense against North Korea, including:

  • Emplace an additional 14 GBIs at Fort Greely, including six at Missile Field 1 (MF-1), which would first be refurbished, and eight into Missile Field 2 (MF-2).
  • Deploy a second forward-based TPY-2 radar to Japan.
  • Conduct Environment Impact Statements to lay some of the groundwork for a potential third GBI site in the eastern United States.134
  • Procure an additional 14 GBIs “to replace those that will now be deployed at Ft. Greely,” in order to “maintain a robust testing program and sufficient operational spares.”
  • Restructure SM-3 IIB efforts into a common kill vehicle technology development program.
PhaseTime FrameGoals
Technology ExplorationFY84-87
  • Evaluate feasibility of potential technologies for defense of United States against ballistic missile attack
SDI Acquisition / TestingFY87-91
  • Begin acquisition of phased homeland ballistic missile defense system
  • Begin acquisition of defenses against limited attack
Shift to TMDFY93-96
  • Develop field theater missile defenses
  • Continue NMD as technology readiness program
  • Discontinue space-based intercept layer
NMD DevelopmentFY96-98
  • Concept development
  • Initial testing and preparation for possible limited deployment
NMD Deployment ReadinessFY98-00
  • Deployment Readiness Review Report
  • 2000 Deferral of Deployment Decision
ABM Treaty WithdrawalFY01
  • Decision announced December 2001, withdrawal effective June 2002
  • MDA creation 2002
Test BedFY02-04
  • Test bed construction (Vandnberg AFB)
  • Build, test, and verify Initial Defensive Capability concurrent with Initial Defensive Operations
  • Incrementally improve capability
Mission Readiness Task Force (MRTF)FY05-06
  • Increase test realism
  • Verify booster and reduce risk
  • Test to verify rather than test to discover
Affordability FocusFY06-08
  • 10 additional silos at Fort Greely
  • 10 GBIs at European third site with 2-stage variant
  • Midcourse radar in Czech Republic
  • Upgrade Thule EWR
Presidential Mandate: RedirectionFY09
  • Refocus on improving confidence through realistic testing
  • Limit fielding to 30 GBIs
  • Expand BMDS capability with EPAA
Return to InterceptFY10-14
  • FTG-06a failure resolved with successful tests
  • GBI reliability improvements
  • Missile Field 2 completion
  • Development and sustainment contract (DSC) award and transition
Secretary of Defense Mandate: 44 by 17FY13-17
  • Increase operational GBI fleet from 30 to 44 by CY 2017
  • Missile Field 1 refurbishment
  • Interceptor reliability enhancements

Many of these steps have now been completed. The second TPY-2 was deployed to Japan in December 2014, and MDA is on track to refurbish MF-1 and emplace the full 14 additional GBIs by the end of 2017. It is not, however, apparent that MDA or the Department of Defense has a plan to procure the additional 14 GBIs for the purpose of testing and as operational spares. As a result, the future testing regime will reduce the number of operationally available GBIs to below 44.

The 2013 report also highlighted the potential for expanding interceptor capacity at Fort Greely well beyond the planned 44 interceptors, with “an additional 20 or more GBIs,” including a mix of two- and three-stage interceptors. The report noted that Fort Greely was originally designed to hold up to 100 interceptors spread across five fields. This latent potential for expansion makes a more “attractive option” for adding interceptor capacity, at least relative to the construction of a new East Coast site.135 The administration did not, however, initiate any further expansion at Fort Greely. The recommendations of the 2013 report that have not yet been acted on are among the logical next steps for further expansion.


    1. James Walker, Lewis Bernstein, and Sharon Lang, Seize the High Ground: The U.S. Army in Space and Missile Defense (Huntsville: U.S. Army Space and Missile Defense Command, 2003), 47; Security Resources Panel, President’s Science Advisory Committee, “Deterrence and Survival in the Nuclear Age,” November 7, 1957, appendix F.
    2. Bradley Graham, Hit to Kill: The New Battle over Shielding America from Missile Attack (New York: Public Affairs, 2003), 291.
    3. James D. Crabtree, On Air Defense (Westport, CT: Praeger, 1994), 62–66.
    4. U.S. Department of Defense, “Conduct of the Persian Gulf War” (Final Report to Congress, April 1992), 219.
    5. James M. Lindsay and Michael E. O’Hanlon, Defending America: The Case for Limited National Missile Defense (Washington, DC: Brookings Institution, 2004), 99.
    6. Ruth Jarrell and Mary T. Cagle, History of the Plato Anti-Missile System: 1952–1960 (Redstone Arsenal, AL: U.S. Army Ordinance Missile Command, 1961), appendix.
    7. Ibid., 6.
    8. Security Resources Panel, President’s Science Advisory Committee, “Deterrence and Survival in the Nuclear Age,” 7.
    9. Ibid., 8.
    10. Ibid., 28–29.
    11. Bell Laboratories, ABM Research and Development at Bell Laboratories: Project History (Whippany, NJ: Bell Labs for U.S. Army Ballistic Missile Defense Systems Command, 1975), I-4.
    12. Ibid., I-3.
    13. Donald R. Baucom, “Space and Missile Defense,” Joint Forces Quarterly (Winter 2002/03): 50–55.
    14. Ernest Yanarella, The Missile Defense Controversy: Technology in Search of a Mission (Lexington: University Press of Kentucky, 2002), 74.
    15. Jacques S. Gansler, Ballistic Missile Defense: Past and Future (Washington, DC: Center for Technology and National Security Policy, 2010), 39.
    16. Missile Defense Agency, “Nike Zeus: The U.S Army’s First Antiballistic Missile,” October 20, 2009, 12.
    17. Ibid., 11.
    18. Defense Special Weapons Agency, “Defense Special Weapons Agency 1947–1997: The First 50 Years of National Service,” 1997, 13.
    19. U.S. Congress, Office of Technology Assessment, Ballistic Missile Defense Technologies, OTA-ITC-254 (Washington, DC: U.S. Government Printing Office, 1985), 45–46.
    20. U.S. Army Center of Military History, History of Strategic Air and Ballistic Missile Defense: Volume II 1956–1972 (U.S. Army, 2009), 212–213.
    21. McGeorge Bundy, “To Cap the Volcano,” Foreign Affairs 48, no. 1 (October 1969): 1–20.
    22. U.S. Army Center of Military History, History of Strategic Air and Ballistic Missile Defense: Volume II, 218.
    23. Committee on an Assessment of Concepts and Systems for U.S. Boost-Phase Missile Defense in Comparison to Other Alternatives, Division on Engineering and Physical Science, National Research Council, Making Sense of Ballistic Missile Defense: An Assessment of Concepts and Systems for U.S. Boost-Phase Missile Defense in Comparison to Other Alternatives (Washington, DC: National Academies Press, 2012), 20.
    24. U.S. Department of State, “Treaty between the United States of America and the Union of Soviet Socialist Republics on the Limitation of Anti-Ballistic Missile Systems,” May 26, 1972, Preamble,
    25. The original wording of the treaty allowed for two sites, one encompassing each party’s national capital, the second encompassing protecting an area containing ICBM silos. A follow-on protocol, signed in 1974, limited this to one site, at the party’s capital or an ICBM field. The protocol went into force May 1976. U.S. Department of State, “Protocol to the Treaty between the United States of America and the Union of Soviet Socialist Republics on the Limitation of Anti-Ballistic Missile Systems,” July 3, 1974.
    26. U.S. Department of State, “Treaty between the United States of America and the Union of Soviet Socialist Republics on the Limitation of Anti-Ballistic Missile Systems,” Article III.
    27. John W. Finney, “Safeguard ABM System to Shut Down; $5 Billion Spent in 6 Years since Debate,” New York Times, November 25, 1975,
    28. William A. Davis Jr., “Reactions and Perspectives,” in Ballistic Missile Defense, ed. Ashton B. Carter and David N. Schwartz (Washington, DC: Brookings Institution, 1984), 381.
    29. U.S. Army SMDC/ARSTRAT Historical Office, “From LoAD to Sentry: Defense of the MX,” Eagle 14, no. 6 (June/ July 2007): 14.
    30. Keith B. Payne and Colin S. Gray, “The Star Wars Debate: Nuclear Policy and the Defensive Transition,” Foreign Affairs 62, no. 4 (Spring 1984): 820–842.
    31. McGeorge Bundy, George F. Kennan, Robert S. McNamara, and Gerard Smith, “Arms Control: The President’s Choice: Star Wars or Arms Control,” Foreign Affairs 63, no. 2 (Winter 1984/85): 264–278.
    32. Strategic Defense Initiative Organization, “The Strategic Defense System Architecture” (Final Report to Congress, January 1988), 2,
    33. David Denoon, Ballistic Missile Defense in the Post–Cold War Era (Boulder, CO: Westview Press, 1995), 125.
    34. Office of Technology Assessment, SDI: Technology, Survivability, and Software, OTA-ISC-353 (Washington, DC: U.S. Government Printing Office, 1988), 9, 17, 125.
    35. Ronald Reagan, “Address to the Nation on Defense and National Security” (speech, Washington, DC, March 23, 1983),
    36. Office of Technology Assessment, SDI, 8.
    37. J. W. Schomisch, ed., 1989 Guide to the Strategic Defense Initiative (Arlington, VA: Pasha Publications, 1989), 34–35.
    38. Henry Cooper and Stephen J. Hadley, “Global Protection against Limited Strikes (GPALS): Briefing on the Refocused Strategic Defense Initiative, Edited Transcript” (presentation, Department of Defense, Pentagon Press Center, Washington DC, February 12, 1991), 81,
    39. Schomisch, 1989 Guide to the Strategic Defense Initiative, 31–32.
    40. U.S. Army SMDC/ARSTRAT Historical Office, “The Homing Overlay Experiment: The First ‘Hit-to-Kill’ Kinetic Energy Interceptor Missile,” Eagle 14, no. 6 (June/July 2007): 11.
    41. Cooper and Hadley, “GPALS: Briefing,” 26–27.
    42. Making Sense of Ballistic Missile Defense, 252.
    43. Tim Weiner, “Inquiry Finds ‘Star Wars’ Tried Plan to Exaggerate Test Results,” New York Times, July 23, 1994.
    44. U.S. General Accounting Office, Ballistic Missile Defense: Records Indicate Deception Did Not Affect 1984 Test Results, GAO/NSIAD-94-219 (Washington, DC: U.S. General Accounting Office, 1994), 3.
    45. Ibid., 4.
    46. Graham, Hit to Kill, 13.
    47. Dwight D. Oland and Cheryl Morai-Young, Department of the Army Historical Summary: Fiscal Year 1984 (Washington, DC: Center of Military History, U.S. Army, 1995), 127.
    48. Schomisch, 1989 Guide to the Strategic Defense Initiative, 130.
    49. Cooper and Hadley, “GPALS: Briefing,” 26–27.
    50. U.S. Government Accountability Office (GAO), Strategic Defense Initiative: Some Claims Overstated for Early Flight Tests of Interceptors, NSIAD-92-282 (Washington, DC: U.S. Government Accountability Office, 1992), 21.
    51. Ibid., 23. There was controversy after the test when program officials mistakenly stated that the ERIS kill vehicle had “discriminated” the target from the decoys. This in fact was not the case. The ERIS EKV engaged a preprogrammed target and did not have the ability to discriminate between decoys and actual targets because the system was designed to rely on Brilliant Eyes satellites that were not deployed. Discrimination was not, however, a stated goal of the test.
    52. Cooper and Hadley, “GPALS: Briefing,” 26–27
    53. U.S. GAO, Strategic Defense Initiatives, 16.
    54. Ibid., 3–23. ERIS program officers noted that the interceptor was required to collect extra testing data pre-intercept and that this additional requirement interfered with the missile making a successful intercept in time.
    55. Schomisch, 1989 Guide to the Strategic Defense Initiative, 132.
    56. Rodney P. Rempt and Marvin J. Langston, “Theater Missile Defense: Technologies to Support a New Naval Mission,” Johns Hopkins APL Technical Digest 14, no. 2 (1993): 145.
    57. Hughes Missile Systems Company, “Navy LEAP: 42 of 43 Objectives Achieved,” 1995.
    58. Walker, Bernstein, and Lang, Seize the High Ground, 66.
    59. James D. Syring, “Homeland Defense” (speech, 2014 Space and Missile Defense Symposium, Huntsville, AL, August 13, 2014).
    60. Office of Technology Assessment, SDI, 12.
    61. Donald R. Baucom, “The Rise and Fall of Brilliant Pebbles,” Journal of Social, Political, and Economic Studies 29, no. 2 (Summer 2004): 143–190.
    62. Ivo H. Daalder, Strategic Defences in the 1990s: Criteria for Deployment (London: International Institute for Strategic Studies, 1991), 24–31.
    63. Eric Schmitt, “3 Republicans Break with Bush over ‘Star Wars,’ ” New York Times, June 16, 1991,
    64. The metric was identified both as “tens to a hundred or so” warheads, and elsewhere “ten to 100 or 200.” Cooper and Hadley, “GPALS: Briefing,” 14.
    65. George H. W. Bush, “State of the Union Address” (speech, Washington DC, January 29, 1991).
    66. Cooper and Hadley, “GPALS: Briefing,” 14.
    67. Office of the Assistant Secretary of Defense (Public Affairs), “Fact Sheet: New Strategic Defense Initiative Program Focus: Global Protection against Limited Strikes (GPALS),” January 30, 1991.
    68. Ibid., 151.
    69. Baucom, “The Rise and Fall of Brilliant Pebbles,” 150, 166.
    70. Cooper and Hadley, “GPALS: Briefing,” 8, 17.
    71. Ibid., 64 (Cooper, response to press question).
    72. The sensors might have expanded for multiple sensor technologies, such as LADAR. Cooper and Hadley, “GPALS: Briefing,” 76.
    73. Ibid., 70 (Cooper, response to press question).
    74. Department of Defense, “Conduct of the Persian Gulf War,” 168.
    75. R. W. Apple Jr., “War in the Gulf: Scud Attack; Scud Missile Hits a U.S. Barracks, Killing 27,” New York Times, February 26, 1991,
    76. U.S. Department of Defense, “Iraq’s Scud Ballistic Missiles,” Information Paper, July 25, 2000, I.
    77. National Defense Authorization Act for Fiscal Years 1992 and 1993, Pub. L. No. 102-190, Division A, Title I, Part C (1991).
    78. Ibid.
    79. Lindsay and O’Hanlon, Defending America, 87.
    80. Department of Defense, “Ballistic Missile Defense Organizational Charter,” Directive, August 18, 1994.
    81. Taylor Dinerman, “The Bush Administration and Space Weapons,” Space Review, May 9, 2005,
    82. Les Aspin, “The End of the Star Wars Era” (news briefing, Office of the Assistant Secretary of Defense, Washington, DC, May 13, 1993).
    83. Eric Schmitt, “Missile Defense Divides G.O.P. on Part of Bill before House,” New York Times, February 16, 1995,
    84. William J. Clinton, “Message to the House of Representatives Returning without Approval the National Defense Authorization Act for Fiscal Year 1996,” in Public Papers of the Presidents of the United States: William Clinton, 1995, Book 2—July 1 to December 31, 1995 (Washington, DC: Government Printing Office, 1995), 1929.
    85. Director of Central Intelligence, “Emerging Missile Threats to North America during the Next 15 Years,” National Intelligence Estimate, NIE 95-19, November 1995.
    86. Commission to Assess the Ballistic Missile Threat to the United States, “Executive Summary of the Report of the Commission to Assess the Ballistic Missile Threat to the United States,” July 15, 1998.
    87. Sheryl WuDunn, “North Korea Fires Missile over Japanese Territory,” New York Times, September 1, 1998,
    88. National Missile Defense Act of 1999, Pub. L. No. 106-38, 113 Stat. 205 (1999).
    89. Bob Walpole, “Foreign Missile Developments and the Ballistic Missile Threat to the United States through 2015,” National Intelligence Council, September 1999.
    90. Steven A. Hildreth and Amy F. Woolf, “National Missile Defense: Issues for Congress,” Congressional Research Service, May 2, 2001, 3.
    91. David C. Gompert and Jeffrey A. Isaacson, Planning a Ballistic Missile Defense System of Systems: An Adaptive Strategy, Issue Paper-181 (Santa Monica, CA: RAND, 1999),
    92. Lindsay and O’Hanlon, Defending America, 83.
    93. Graham, Hit to Kill, 282.
    94. Lindsay and O’Hanlon, Defending America, 89.
    95. Graham, Hit to Kill, 80. Article III of the ABM Treaty required that missile defense radars had to be colocated with interceptors.
    96. Lindsay and O’Hanlon, Defending America, 83, 99.
    97. Syring, “Homeland Defense.”
    98. Lindsay and O’Hanlon, Defending America, 93.
    99. Graham, Hit to Kill, 92.
    100. Ibid., 214.
    101. Amy F. Woolf, “Anti-Ballistic Missile Treaty Demarcation and Succession Agreements: Background and Issues,” Congressional Research Service, April 27, 2000.
    102. Graham, Hit to Kill, 266.
    103. Ibid., 289.
    104. Eric Schmitt, “Clinton’s Missile Decision: The Overview; President Decides to Put Off Work on Missile Shield,” New York Times, September 2, 2000,
    105. William Clinton, “Remarks by President Bill Clinton on National Missile Defense” (speech, Georgetown University, Washington, DC, September 1, 2000).
    106. George W. Bush, “Remarks by the President on National Missile Defense” (speech, Rose Garden, Washington DC, December 13, 2001).
    107. Donald Rumsfeld, “Missile Defense Program Direction,” Office of the Secretary of Defense Memorandum, January 2, 2002.
    108. The 2001 NPR list of near- and mid-term options included “a single Airborne Laser for boost-phase intercept, a rudimentary ground-based midcourse system, consisting of a small number of interceptors taking from the test program . . . and, a sea-based Aegis system {that} could be available to provide a rudimentary midcourse capability against short to medium-range threats.” The list of “operational capabilities” for the 2006–2008 period included “2–3 Airborne Laser aircraft, additional ground-based midcourse sites, 4 sea-based midcourse ships, Terminal systems, able to defend against shorter-range threats: PAC-3 . . . and THAAD, which could be available by 2008.” Department of Defense, Nuclear Posture Review (Washington, DC: Department of Defense, 2001), 26.
    109. George Bush, National Policy on Ballistic Missile Defense (Washington, DC: The White House, National Security Presidential Directive-23, 2002).
    110. Graham, Hit to Kill, 361.
    111. Bush, “National Policy on Ballistic Missile Defense.”
    112. “Joint Declaration by President George Bush and President Vladimir Putin on the New Strategic Relationship between the United States of America and the Russian Federation,” White House, Office of the Press Secretary, May 24, 2002.
    113. Lieutenant General Ronald T. Kadish, “Reorganization of the Missile Defense Program” (statement before the Senate Armed Services Committee, Strategic Forces Subcommittee, March 13, 2002).
    114. Bush, “National Policy on Ballistic Missile Defense.”
    115. Steven Lambakis, The Future of Homeland Missile Defenses (Fairfax, VA: National Institute Press, 2014), 14.
    116. “Fact Sheet: Defending America and Its Allies against Ballistic Missile Attack,” White House, Office of the Press Secretary, October 23, 2007.
    117. Bruce Konviser, “U.S. Missiles in E. Europe Opposed by Locals, Russia,” Washington Post, January 28, 2007,
    118. Steven A. Hildreth and Carl Ek, “Long-Range Ballistic Missile Defense in Europe,” Congressional Research Service, September 23, 2009, 7.
    119. U.S. Department of State, “Agreement between the Government of the United States of America and the Government of the Republic of Poland concerning the Deployment of Ground-based Ballistic Missile Defense Interceptors in the Territory of the Republic of Poland,” August 20, 2008; U.S. Department of State, “Agreement between the United States and the Czech Republic on Establishing a United States Ballistic Missile Defense Radar Site in the Czech Republic,” July 8, 2008.
    120. Robert Gates, “Defense Budget Recommendation Statement” (speech, Arlington, VA, April 6, 2009).
    121. “U.S. Kills Northrop Grumman Missile-Defense Program,” Reuters, June 11, 2009,
    122. “U.S. Missile Defense Policy a Phased, Adaptive Approach for Missile Defense in Europe,” White House, Office of the Press Secretary, September 17, 2009.
    123. Henry A. Obering III, “The Future of Global Missile Defense” (speech, Huntsville, AL, August 15, 2016), Defense One Panel Discussion,
    124. Missile Defense Agency, “Missile Defense Agency Awards Contracts to Support Concept Definition and Program Planning for the Standard Missile 3 (SM-3) Block IIB Program,” MDA news release, April 7, 2011.
    125. Although MDA statements usually indicate 30 as the maximum number of interceptors “available” or which have been “emplaced” over time, the number emplaced at any given time more likely did not rise above 29 for the 2010–2012 period. The number of interceptors emplaced is not identical to the number operationally available. At any given day, as with other missile systems, some silos or interceptors may be operationally unavailable due to maintenance or upgrades.
    126. U.S. Department of Defense, Ballistic Missile Defense Review Report (Washington, DC: DoD, 2010), iv.
    127. Jaganath Sankaran, “Missile Defense against Iran without Threatening Russia,” Arms Control Today, November 4, 2013,
    128. Senator Joseph Lieberman, “The President’s Decision on Missile Defense in Europe” (statement during hearing of the Senate Armed Services Committee, 111th Cong., 1st sess., September 24, 2009).
    129. U.S. Government Accountability Office (GAO), Standard Missile-3 Block IIB Analysis of Alternatives, GAO-13-382R (Washington, DC: U.S. Government Accountability Office, 2013), 7.
    130. Ibid., 26.
    131. David E. Sanger and Choe Sang-Hun, “North Korea Confirms It Conducted 3rd Nuclear Test,” New York Times, February 11, 2013,
    132. “U.S. Scraps Final Phase of European Missile Shield,” BBC, March 16, 2013,
    133. U.S. Department of Defense, “Homeland Defense Hedging Policy and Strategy” (Report to Congress, June 2013), 3.
    134. These studies had been mandated by Congress in the FY 2014 National Defense Authorization Act.
    135. Department of Defense, “Homeland Defense Hedging Policy and Strategy,” 4–5.