- Executive Summary
- Chapter 1 | Homeland Missile Defense in U.S. Strategy
- Chapter 2 | The Evolution of Homeland Missile Defense
- Chapter 3 | The State of Homeland Missile Defense Today
- Chapter 4 | Ground-based Interceptor Development
- Chapter 5 | Sensors and Command and Control
- Chapter 6 | Future Options
Note: This appears as Chapter 1 in Missile Defense 2020: Next Steps for Defending the Homeland.
Missile defenses for the homeland now represent an established part of U.S. national security strategy and policy, and the first priority of U.S. missile defense efforts, even while the particular programs, budget levels, and metrics of sufficiency have varied over time. Sometimes long-range missile threats to the homeland have been assessed as more urgent; at other times, regional missile defenses have received more emphasis.
Global proliferation trends reflect a range of threats increasing in complexity, number, and capabilities, with missiles becoming more accurate, mobile, prompt, and survivable. Besides purely ballistic threats, new adversary capabilities now include a range of cruise missiles and maneuvering boost-glide vehicles. Should these missile trends continue, the demand for ways to defend against and defeat them will also continue to rise.
Throughout the long history of efforts to protect against missile attack, active missile defense has never truly been a substitute or replacement for offensive retaliatory capabilities within the overall U.S. strategic posture. Some forms of passive defense against missiles have also never been controversial, such as hardening ICBM silos and putting missiles undersea and aircraft on alert. In terms of active defenses, there has been considerable variation between the objects of defense, the identity of the adversaries against whom defenses were directed, and the thickness or thinness of the defense pursued.
President Reagan’s aspirations for the Strategic Defense Initiative (SDI) were perhaps too optimistic in the hope to make nuclear weapons and their delivery vehicles “impotent and obsolete.” At times, the goal of SDI has been depicted as a perfect defense against everything the USSR could throw. Later, its Phase 1 architecture would focus on complicating Soviet nuclear strike and thereby strengthening deterrence. Reagan’s 1983 SDI speech also contained caveats. While taking note of recent technological advancement, he described the challenge as “a formidable, technical task, one that may not be accomplished before the end of the century,” predicting “failures and setbacks, just as there will be successes and breakthroughs.”1
Recent U.S. policy does not seek missile defenses to safeguard the American homeland against either large- or small-scale missile attacks by Russia or China, preferring to rely on offensive-based deterrence to address these threats. The focus of U.S. missile defense has instead been to counter the limited and emerging ICBM threats from rogue states such as North Korea and Iran. This policy reflects two factors: the desire to not disrupt “strategic stability” with Russia or China, and the costs and technical limitations of such a system. This basic posture is evidenced in the characteristics, capacity, and capabilities of GMD.
These general expectations for homeland missile defense reflect significant continuity across at least the past two administrations, as indicated by high-level expressions of U.S. policy and strategy.2 In 2008, Secretary of State Condoleezza Rice remarked, “It is true that the United States once had a Strategic Defense Initiative, a program that was intended to deal with the question of the Russian strategic nuclear threat. This is not that program. This is not the son of that program. This is not the grandson of that program.”3 Undersecretary of State Rose Gottemoeller made a similar point in a November 2014 speech in Bucharest. Addressing the perennial Russian and Chinese complaints about U.S. missile defenses as destabilizing, Gottemoeller noted that “our limited numbers of defensive systems cannot even come close to upsetting the strategic balance.”4 As she pointed out, even the plan for 44 homeland defense interceptors is 24 fewer than the 68 interceptors deployed around Moscow, but of course the United States is not concerned about the impact of those 68 on strategic stability.
Former vice chairman of the Joints Chief of Staff, Admiral James Winnefeld, addressed the issue in 2015, noting that “we prefer to use the deterrent of missile defense in situations where it has the highest probability of being most effective; we’ve stated missile defense against these high-end threats is too hard and too expensive and too strategically destabilizing to even try.”5 Rejecting the attempt to degrade the Russian strategic deterrent is not the same, however, as saying that the United States would never use regional or homeland missile defenses against a Russian or Chinese missile. Indeed, even while disavowing the ambition to defeat large-scale Russian or Chinese missile attacks and “affect the strategic balance,” the 2010 Ballistic Missile Defense Review (BMDR) explicitly says that the “GMD system would be employed to defend the United States against limited missile launches from any source.”6
While this basic posture has been accepted toward Russia and perhaps China, U.S. policymakers have expressed an unwillingness to engage in a “balance of terror” type strategic relationship with rogue nations such as North Korea. The George W. Bush administration, for instance, noted that “the strategic logic of the past may not apply to these new threats, and we cannot be wholly dependent on our capability to deter them.”7 Speaking of North Korean leader Kim Jong-un, the commander of U.S. Northern Command (NORTHCOM), Admiral William Gortney, has likewise more recently commented, “We can live with some pretty ugly opponents as long as they are predictable. This guy we just can’t . . . predict.”8
Of course, this general posture of pursuing “limited” national missile defense could well change. A future administration could conceivably decide that long-range missile defense was too difficult or costly at the margin and choose to accept vulnerability, even with states like North Korea, and rely exclusively on offensive means of deterrence.9 Such a choice would represent a significant discontinuity from the past. The Clinton administration began the NMD program in part based on the increasing realization that relying on purely offensive deterrence with North Korea simply did not seem to make sense. As President Clinton himself later put it, “You can’t be an internationalist if you allow yourself to be blackmailed.”10 Such an offensive deterrence-only relationship with North Korea seems unlikely.
|1999 NMD Act||FY 2017 NDAA|
|It is the policy of the United States to deploy as soon as is technologically possible||It is the policy of the United States to maintain and improve|
|an effective National Missile Defense system||an effective, robust layered missile defense system|
|capable of defending the territory of the United States||capable of defending the territory of the United States, allies, deployed forces, and capabilities|
|against limited ballistic missile attack (whether accidental, unauthorized, or deliberate)||against the developing and increasingly complex ballistic missile threat|
|with funding subject to the annual authorization of appropriations and the annual appropriation of funds for National Missile Defense.||with funding subject to the annual authorization of appropriations and the annual appropriation of funds for National Missile Defense.|
U.S. missile defense policy and posture are predicated on the principle that the United States homeland cannot be held hostage by a country such as North Korea. As Admiral Gortney remarked in April 2016, “We are concerned the possession of a nuclear ICBM could embolden the [North Korean] regime’s intransigence below the nuclear threshold and complicate our response to a crisis on the peninsula.”11 As such, a limited long-range missile defense serves the strategic purpose of giving “the United States . . . the freedom to employ whatever means it chooses to respond to aggression without risk of enemy escalation to homeland strikes.”12 This freedom of action supports allied confidence that the United States will live up to its alliance commitments, lowering the risk of alliance decoupling. Assurance of allies in turn strengthens extended deterrence, helps promote regional stability, and fosters an environment more favorable to nonproliferation.
The goals of homeland missile defense might alternatively be revised upward, to include protection against not only attacks from North Korea and Iran, but to provide a thin defense against certain kinds of limited missile attack from Russia or China. Such a defense could include either protection for U.S. population centers or for nuclear and other strategic forces so as to enhance rather than undermine strategic stability. The objectives of homeland defense might also be expanded to include nonballistic missiles. Hypersonic boost-glide vehicles have recently begun to get more research and development attention, but there remains virtually no significant capability to defend against cruise missile attack on the National Capital Region.
The National Defense Authorization Act passed in late 2016 revises the 1999 formulation (Table 1.1), declaring that U.S. policy is to “maintain and improve an effective, robust layered missile defense system capable of defending the territory of the United States, allies, deployed forces, and capabilities against the developing and increasingly complex ballistic missile threat.”13 The conference report further added that “nothing in this legislative provision requires or directs the development of missile defenses against any country or its strategic nuclear forces.”14 For the time being, much more remains to be done simply to keep pace with the existing threat set.
Homeland missile defense can also improve crisis stability by offering the United States an option other than preemption or retaliation. This is especially true when dealing with smaller “rogue” states against which the United States might take preemptive military action during a crisis. In the lead-up to North Korea’s Taepodong-2 launch in 2006, GMD may have lessened the pressure on President Bush to preemptively strike North Korea’s launch facilities, a course of action advocated at the time by former secretary of defense William Perry and then former assistant secretary of defense Ashton Carter.15 Such a posture buys time and creates options for decisionmakers, which in turn supports stability.
Another example of a stabilizing dynamic is found in the October 2016 attacks on the USS Mason (DDG-87), in which antiship cruise missiles were reportedly fired at the vessel as it sailed off the coast of Yemen. Instead of being hit (as was a United Arab Emirates navy ship just days prior), the ship fired SM-2 Block IV and Evolved Sea Sparrow Missile (ESSM) interceptors, as well as apparently employing other electronic countermeasures. The missiles did not hit the ship. Had the ship been damaged or sunk, there might have been substantial pressure to widen U.S. presence and engagement with Houthi forces in Yemen. Instead, the United States had the time to assess the situation and decide how to respond, choosing to limit its response to Tomahawk cruise missile strikes against coastal radar facilities that purportedly directed the attack.16
Homeland missile defense also serves the purpose of raising the threshold for aggression for an adversary wishing to undertake military action against the United States. Having the ability to defend against a certain number of long-range missiles requires an adversary to employ a greater number of missiles to achieve the same objective, thus making a “cheap shot” against the American homeland or military forces more difficult. Forcing an adversary to thus increase the size of an attack increases the likelihood that preparations for such an attack will be detected in advance, creating opportunities for the United States to either de-escalate the crisis or take preemptive strikes.
The fielding of a limited yet effective long-range missile defense system could contribute to a secondary deterrence-by-denial effect, whereby emerging regional challengers are dissuaded from investing in long-range ballistic missile technology. Without insight on the inner working of Iranian or North Korean strategy and U.S. resource allocation deliberations, however, this potential effect remains difficult to assess. Missile defenses have come a long way, but have thus far not dissuaded proliferators that missiles are impotent or obsolete.
Today, nearly 30 countries maintain ballistic missile capabilities, with approximately 50 ballistic missile variants.17 The missile defense mission has grown more challenging as antagonists now possess capabilities that are more robust, accurate, and diverse, threatening U.S. and allied forces both at sea and on land. In a November 2014 memo to the secretary of defense, Chief of Naval Operations Admiral Jonathan Greenert and Chief of Staff of the Army General Raymond Odierno jointly wrote of “growing challenges associated with ballistic missile threats that are increasingly capable, continue to outpace our active defense systems, and exceed our Services’ capacity to meet Combatant Commanders’ demand.”18
Looking ahead, the United States and its allies and partners may expect to encounter more multifaceted threats that could overcome current defense systems, including advanced cyber intrusions, electronic warfare, directed energy, and hypersonics. MDA has been assigned responsibility for the hypersonic mission, but not the funds to do much about it. Future decisionmakers will have to consider whether MDA should retain its near-exclusive focus on material development for the ballistic missile defense mission or expand its mandate to address the broader suite of cruise missile, air defense, and hypersonic threats.
Research and development has always been at the institutional and conceptual center of ballistic missile defense efforts. In particular, the steady advance of missile technology creates an imperative for missile defense technology to “outpace the threat.” Unfortunately, MDA’s research and development efforts have been steadily declining, in both real dollars and in relative terms to MDA’s overall (but also declining) topline budget.19 The strain on MDA’s investment in advanced technology is one of several concerning manifestations of what Secretary of Defense Ashton Carter and others have called the temptation to “eat our seed corn.”20 Undersecretary Frank Kendall has likewise stressed the importance of research and development: “Just patching the things we’ve got is probably not going to be adequate . . . we’re going to have to go beyond that.”21 MDA and congressional leadership have also echoed these warnings.22
As of today, Iran and North Korea have not yet, strictly speaking, demonstrated an ICBM with a flight test. Nevertheless, both have extensive missile development programs, have deployed a significant number of medium- and intermediate-range missiles, and put satellites into orbit, all major steps critical to ICBM development.
Much attention has been given to whether Iran or North Korea could acquire an ICBM by the year 2015. For at least 15 years, intelligence reports and testimony continued to peg threat assessments to the 2015 time frame. Now that 2015 has come and gone, some observers have questioned the validity of previous U.S. assessments on rogue state ICBM development.23 It could well be, however, that actions taken on the basis of those intelligence assessments may have had some effect on preventing the past potentialities from being actualized. The United States and others have not stood idly by with missile developments by Iran, North Korea, and others. They have rather engaged in a systematic range of counterproliferation and nonproliferation efforts, ranging from diplomacy and sanctions to interdiction and, reportedly, various forms of sabotage. Relying on indefinite counterproliferation success in the absence of active defenses, however, also carries considerable risk.
“It is difficult to predict precisely how the threat to the U.S. homeland will evolve,” the BMDR noted in 2010, “but it is certain that it will do so.”24 The overall trend line is that both ballistic and nonballistic missile threats to the United States homeland are growing, with little indication of relief. In the words of one observer, “There are no projections within the U.S. intelligence community showing a decline in the number of ballistic missiles in the world and no evidence at all that we will ever be without nuclear weapons.”25 The United States has been surprised before with foreign missile developments and may be again. The former deputy assistant secretary of defense for nuclear and missile defense policy, Elaine Bunn, has remarked on the importance of being “humble” about making threat predictions.26
North Korea has invested much of its military resources to improve its ballistic missile and nuclear weapon capabilities, which together provide an ability to hold at risk military and civilian targets. A fourth North Korean nuclear test was conducted in January 2016, followed by a fifth in September that year. Their short- and medium-range systems include a host of artillery and short-range rockets, a newer mobile solid-fueled SS-21 variant called KN-02, legacy Scud missiles, and a No-Dong MRBM.27
North Korea conducted eight Musudan IRBM tests in 2016, with its sixth test in June 2016 achieving “partial success” (see Figure 1.2). Although the missile had a lofted trajectory, it did appear to complete a full ballistic flight. Another Musudan launched just hours before appeared to have disintegrated shortly after launch. North Korea tested the same missile twice more in October 2016, but apparently without success. Despite these mixed results, the earnestness of North Korea’s testing regime demonstrates a commitment to the Musudan’s development. The missile is estimated to have a range of around 3,500 to 4,000 kilometers (km), putting it within striking distance of U.S. military bases in Japan and possibly Guam.28
North Korea also possesses a Satellite Launch Vehicle (SLV), the Unha-3, which was used to successfully orbit a small satellite in December 2012 and January 2016, thus indicating North Korea’s capabilities for a number of long-range missile technologies.
North Korea’s SLV experiments may be informing the development of a new class of North Korean ICBMs. In 2012, North Korea began to display a road-mobile ICBM designated KN-08, also known as Hwasong-13. In October 2015, another variant dubbed the KN-14 made its appearance at the Worker’s Party of Korea annual parade. Neither variant has been flight-tested, but the missile’s estimated range is between 5,000 and 9,000 km, giving it the potential to strike the U.S. West Coast and parts of the northern Midwest.29 Pyongyang has also made surprisingly rapid progress toward a submarine-launched ballistic missile capability, with an apparently successful test launch of its KN-11 SLBM in August 2016.30
The heads of U.S. Forces Korea (USFK) and of NORTHCOM have both suggested that North Korea has the capability to miniaturize a nuclear weapon for the KN-08.31 In March 2016, images released by the Korean Central News Agency (KCNA) featured North Korean leader Kim Jong-un inspecting what appears to be a miniaturized nuclear device.32 The validity of these photographs has not been verified, however, and North Korea has been known to use mock-ups in state propaganda in the past. Images released of ground tests on the reentry vehicle heat shield, and of more advanced missile engine tests, are made to leave the impression that North Korea is progressing in its long-range ballistic missile capabilities and is not deterred or slowed by international sanctions.
Iran maintains the most active and diverse ballistic missile program in the Middle East, amassing more than 800 short- and medium-range missiles capable of striking targets within its region and southeastern Europe. While engaging in significant transnational cooperation with North Korea and likely Pakistan, Iran has made major progress in the overall reliability of its missiles. These include the Shahab-3 series (which includes the Ghadr and Emad variants), the solid-fueled Sejjil and Fateh-110, along with the recently revealed Fateh 313, Qiam, and the Fajr-3.33 It is likely, however, that Iran’s ballistic missiles currently lack the accuracy to effectively destroy critical military and infrastructure targets with conventional warheads, at least without large salvo attacks.34 Iran has yet to display or flight-test an ICBM. Most of Iran’s longer-range missiles have demonstrated a range of around 2,000 km. To reach the United States from Iran, an ICBM would need a range of over 9,000 km.35
Iran has also used its long-range rockets to put satellites into orbit, with its fourth launch occurring in February 2015. Over the past decade, Iran has conducted numerous tests of the two-stage Safir SLV and has been developing a larger two-stage SLV dubbed the Simorgh, which Iran reportedly tested in April 2016 with unclear results.36 Many of the technologies developed for these SLV programs could be applied to creating an ICBM.37 Where SLV and ICBM technologies differ, however, is the ICBM’s need for a reentry vehicle capable of reentering the atmosphere and detonating a nuclear device.38 Iran has not yet demonstrated these capabilities.
Iran nonetheless appears intent on maintaining and continuing development of its missile programs. Since the signing of the 2015 Joint Comprehensive Plan of Action (JCPOA) and despite restrictions by United Nations Security Council Resolution 2231, Iran’s missile testing has continued and even accelerated. This has included recent launches of Emad, reportedly a Shahab-3 variant with a maneuvering reentry vehicle (MaRV) to improve accuracy.39 The regime’s use of mobile launchers and underground tunnels below silo-like launch hatches will make it more challenging for the United States or others to target the missiles prior to launch.40
Both Russia and China have formidable strategic assets. Russia possesses over 300 ICBMs equipped with multiple independent reentry vehicles (MIRVs), as well as over 175 SLBMs deployed across 11 submarines, all capable of delivering nuclear payloads to the United States.41 Russian missiles are furthermore described as having been designed to defeat U.S. missile defenses, including with decoys and other sophisticated countermeasures and penetration aids. China, for its part, deploys more than 60 ICBMs holding the continental United States at risk, and it is currently developing a modern fleet of nuclear ballistic missile submarines equipped with nuclear-tipped SLBMs with a reported range of over 7,000 km.
The magnitude of the threat from these near-peer actors makes building a robust missile defense against them a significant challenge. It seems unlikely that the United States would attempt in the near term to shift toward a defense dominant posture with respect to Russian and Chinese long-range missile forces, but homeland missile defense need not forswear attention to these threats entirely. In the past, the United States has pursued thin or point defenses to support deterrence and enhance strategic stability with Russia or China, such as with Sentinel, Safeguard, and LoAD (see Chapter 2). Given the past decade’s developments in the demonstrated hypersonic and cruise missile capabilities of Russia and China, missile defenses of various kinds could support the survivability of U.S. nuclear forces. The dynamic between strategic forces and active missile defense could perhaps figure in the next U.S. nuclear posture review.
Another threat to the U.S homeland increasingly highlighted by senior U.S. military officials is the threat posed by long-range cruise missiles possessed by Russia, and their proliferation around the globe. Once advanced technology possessed only by the superpowers, cruise missiles are now widely acquired, including by such countries as Pakistan (Hatf 7,8), North Korea (KN-01), Iran (Soumar), and others.42
Vice Admiral James Winnefeld, then vice chairman of the Joint Chiefs of Staff, remarked in 2015 that “homeland cruise missile defense is shifting above regional ballistic missile defense, in my mind, as far as importance goes.”43 More recently, NORTHCOM Commander William Gortney, commenting on Russia’s conspicuous employment of long-range SS-N-30 cruise missiles to hit targets in Syria, told Congress that “there’s no operational or tactical requirement to do it. They’re messaging us that they have this capability.”44
Russia moreover openly markets for export highly portable cruise missiles that could be used to threaten the United States homeland. The Klub-K missile is derived from the SS-N-27 Sizzler, whose shorter range falls within arms control export regimes. It can also fit inside a cargo container, making it easy to transport and potentially launch from a ship or undersea platform of some kind.45 In addition to the element of surprise these systems could bring, they also provide mobility and could be fired from locations such as the Gulf of Mexico or elsewhere to evade some U.S. early warning sensors.
The ballistic and cruise missile threats to the United States and its allies are not diminishing. In the coming years, North Korea could well enter into serial production of intercontinental ballistic missiles. Iran has also shown no sign of abandoning its long-range efforts. It would be quite difficult and costly to face a situation of significantly greater threats in, say, 2025, and attempt to catch-up. Outpacing rather than chasing these threats will require increased effort.