The Nuclear Notebook is researched and written by Hans M. Kristensen, director of the Nuclear Information Project with the Federation of American Scientists, and Matt Korda, a research associate with the project. The Nuclear Notebook column has been published in the Bulletin of the Atomic Scientists since 1987. This issue examines the status of US missile defense, a key driver of the global nuclear arms race. According to the latest Missile Defense Review, the United States will continue to enhance its four primary missile defense systems – one for homeland defense and three for regional defense – without “any limitation or constraint.” Doing so is likely to be destabilizing, as potential adversaries will attempt to build offensive systems to offset the United States’ defensive systems. This dynamic is currently on display with Russia and China, both of which are developing missiles that are specifically designed to counter US missile defenses.
Missile defense systems can have a significant effect on nuclear weapons postures, the strategy for their potential use, and crisis stability and international security. The defenses don’t even have to work very well; the uncertainty that they might work, or could become more capable in the future, are enough to trigger the effect. Advocates argue that missile defenses don’t threaten anyone and can help deter adversaries, but those adversaries are unlikely to simply give up; they are more likely to be stimulated to try to beat the defenses to ensure their own deterrent forces remain effective and credible. This dynamic is clear from many cases during the Cold War and remains evident today.
On balance, it is difficult to see what real national security benefits the United States has achieved from decades of missile defense research and development. While defense of a forward base of a limited size may be possible, the promise of a credible defense of the homeland remains doubtful. Instead of assured security, missile defenses have helped to harden adversarial perceptions of US intentions and fueled development of more capable offensive capabilities directed against the United States and its allies.
In response to actual or suspected missile defense capabilities, the nuclear-armed states undertook substantial modernization programs during the Cold War. When the Soviet Union built missile defense systems around Moscow and Leningrad (now St. Petersburg), the United States responded by creating a designated nuclear strike plan with over 100 intercontinental ballistic missiles (ICBMs) and submarine-launched ballistic missiles (SLBMs) to be able to defeat the defenses (Kristensen, McKinzie, and Norris 2004). This inclination to try to overwhelm the defenses helped stimulate development of missiles with multiple reentry vehicles and later independently targetable reentry vehicles (MIRVs). These technological advances led to a massive nuclear weapons buildup in the 1970s and 1980s.
The ABM treaty
In recognition of the effect that missile defense can have on strategic stability and the buildup of offensive forces, the United States and the Soviet Union signed the Anti-Ballistic Missile (ABM) Treaty in 1972, thus limiting each country’s ability to deploy missile defenses on their territory. The logic governing the treaty suggested that if either country could manage to deploy effective missile defenses, strategic stability could be immediately disrupted by the “ragged second strike” problem – the prospect that one country could wipe out most of the other country’s nuclear forces in a first strike, and rely on robust missile defenses to mop up the few remaining missiles launched in retaliation. However, if the two superpowers remained mutually vulnerable to each other’s nuclear forces, then they would be deterred from launching a first strike. Therefore, the absence of effective missile defenses was critical in maintaining strategic stability between the United States and the Soviet Union.
The ABM Treaty specifically limited each side to one regional ABM site of 100 ground-based missile interceptors, to protect either the capital or an ICBM field. The Soviet Union chose to protect Moscow; the United States chose to protect an ICBM base near Grand Forks, North Dakota. Moscow’s ABM defenses are still operational today; however, the Grand Forks interceptor site was shut down within months of activation due to financial constraints and its presumed ineffectiveness. The treaty’s other key provisions also prohibited either country from developing sea-, air-, space-, or mobile land-based ABM systems; upgrading non-ABM systems to have ABM capabilities; and deploying ballistic missile early-warning radars or ABM systems anywhere other than on US or Soviet territory (Kimball and Reif 2012).
These prohibitions are no longer in force, because the United States withdrew from the ABM Treaty in 2002. At the time, President George W. Bush claimed the treaty was no longer relevant to US-Russia relations in the post–Cold War era and that the treaty prevented the United States from developing missile defenses against “rogue” states such as North Korea and Iran that might not be deterred by US nuclear forces.
At the time, both Russia and China warned that if the defenses became too capable, they would be forced to take countermeasures to ensure the effectiveness of their deterrent. The head of the Russian armed forces warned that the US decision “will alter the nature of the international strategic balance in freeing the hands of a series of countries to restart an arms buildup” (Neilan 2001). To reassure Russia and China, the Bush administration, and subsequently also the Obama administration, insisted US missile defense systems were not intended to defeat Russian and Chinese missiles but only to protect against attacks from “rogue” states with limited missile capabilities.
Russia never believed the US reassurances. Nor did China accept them. Both started and expanded development of capabilities that would be able to defeat the US missile defenses if necessary. In a speech in March 2018, Russian president Vladimir Putin unveiled a series of exotic new strategic weapons that he claimed were specifically designed to overcome US missile defenses. Putin emphasized that the ABM Treaty had been the cornerstone of US-Russian strategic stability, but at the time “nobody wanted to listen to us. So listen now” (Putin 2018). To this day, Putin maintains that the renewed arms race began “when the US withdrew from the ABM Treaty” (TASS 2018).
Russia is also upgrading the missile defenses around Moscow. The refurbished system, known as A-235, will include enhanced short-range interceptors. Russian S-300 and S-400 air-defense systems reportedly have a limited capability against shorter-range ballistic missiles, and the longer-range S-500 in development is rumored to have a capability to intercept ICBM warheads during reentry – although such rumors must be viewed with caution (TASS 2019; RIA Novosti 2017).
China, for its part, has reacted to the US missile defense systems by developing MIRVs for its ICBMs. The large silo-based DF-5 has been retrofitted to carry MIRVs, and the new road-mobile DF-41 is also capable of carrying MIRVs. This capability is intended to ensure that China’s limited ICBM force is capable of penetrating the US national missile defense system. Likewise, several new medium- and intermediate-range missile systems are equipped with a maneuverable reentry vehicle (DF-26) or a glide vehicle (DF-17), partly to overcome regional missile defenses.
The Trump administration
The Trump administration’s Missile Defense Review appeared to continue the policy of the previous administrations to limit the role of missile defenses against “rogue” states: “US missile defense capabilities will be sized to provide continuing effective protection of the US homeland against rogue states’ offensive missile threats.” For the larger and more sophisticated ballistic missile capabilities of Russia and China, the “United States relies on nuclear deterrence” (US Department of Defense 2019a, IX).1
But President Donald Trump immediately created doubts about this by describing an unlimited missile defense strategy directed against any missile from anywhere. In his official remarks at the Pentagon, Trump said the goal of the Missile Defense Review was to “ensure that we can detect and destroy any missile launched against the United States – anywhere, anytime, anyplace.” This would require adjusting the posture to “defend against any missile strikes, including cruise and hypersonic missiles.” Since North Korea and Iran are not developing hypersonic missiles, this was seen as a tacit reference to Russia and China. Trump seemed to remove any doubt when he declared the United States “will terminate any missile launches from hostile powers, or even from powers that make a mistake. It won’t happen. Regardless of the missile type or the geographic origins of the attack, we will ensure that enemy missiles find no sanctuary on Earth or in the skies above” (The White House 2019).
Today, the United States has deployed a suite of once-prohibited ABM systems across the globe (see Figure 1) and is in the midst of a robust modernization process for these systems (see Figure 2). Both US official statements and Russian and Chinese reactions assume the systems work as intended. However, there are strong indications that some parts are much less capable than advertised.2 Moreover, even the best missile defenses can be relatively easily fooled by countermeasures or overwhelmed. The following sections provide a quick overview of the management, capabilities, and status of the various missile defense programs.
Figure 1. Current homeland missile defense architecture (US Department of Defense 2019a, 42). UEWR = upgraded early warning radar.
Figure 2. US homeland missile defense growth (US Department of Defense 2019a, 59). UEWR = upgraded early warning radar. GBI = ground-based interceptor.
Missile defense agency
The Missile Defense Agency (formerly the Ballistic Missile Defense Organization) is responsible for research and development of US missile defense systems. The MDA’s mission is “to develop and deploy a layered Missile Defense System to defend the United States, its deployed forces, allies, and friends from hypersonic and ballistic missile attacks of all ranges and in all phases of flight” (Missile Defense Agency 2019c).
Despite the fact that the MDA has received about $142 billion in funding from 2002 to 2017 (Government Accountability Office 2019, 1), the agency has been notoriously plagued by a variety of technical, quality control, and cultural issues. The MDA has been criticized by other elements of the US government, including the Government Accountability Office (GAO) and the Defense Department Inspector General, for prioritizing “schedule-driven milestones, rather than pursuing a knowledge-based approach” (Government Accountability Office 2019, 26).
Particularly with regards to Ground-based Midcourse Defense (GMD), this approach has resulted in systems being deemed operational before being fully tested, thus failing to address outstanding technical defects. For example, a 2014 Defense Department Inspector General report discovered 48 “nonconformances” within the Exoatmospheric Kill Vehicle – the intercept component of the Ground-based Midcourse Defense – that constituted violations of aerospace standards. Twenty-two of these violations were considered “major,” meaning “a nonfulfillment of a requirement that is likely to result in the failure of the quality management system or reduce its ability to ensure controlled processes or compliant products/services” (US Department of Defense 2014, 9–10). This likely explains why the GAO assessed that same system – which has cost approximately $67 billion thus far (Reif 2019a) – to have achieved “less than 50 percent operational realism” (Government Accountability Office 2019, 59). In the same 2019 report, the GAO noted that the “MDA did not meet its planned goals,” noting that the MDA only completed 64–70 percent of its planned deliveries and tests for fiscal year 2018 because of “failures, cancellations, and delays” (Government Accountability Office 2019, I).
Perhaps the best summation of the MDA’s inefficiency and wastefulness can be attributed to the GAO, which somewhat passive-aggressively stated in a recent report: “Our prior work has shown that stabilizing system design before making major production commitments and relying on knowledge rather than deadlines to make acquisition decisions at key milestones are best practices of successful product developers” (Government Accountability Office 2019, 52).
In March 2018, the MDA suddenly decided to classify information about pending missile defense flight tests, their objectives, and their timing. However, beyond citing “the need to safeguard critical defense information,” the decision to classify this previously public information has not been adequately explained (Aftergood 2018). In July 2018, Congress rejected and overrode the MDA’s decision, adding a new provision to the fiscal year 2019 National Defense Authorization Act that required “that MDA make the quarter and fiscal year of execution of planned flight tests unclassified” (NDAA 2019, Sec. 1681).
Homeland missile defense
The US homeland missile defense system is known as Ground-based Midcourse Defense, which is designed to intercept strategic ballistic missile warheads while they are traveling in their midcourse phase of flight. The system consists of a multistage ground-based missile interceptor equipped with an exoatmospheric kill vehicle. GMD relies on “hit-to-kill” technology; after separating from its booster, the kill vehicle seeks out its target in space and destroys it through direct collision.
There are currently 44 ground-based interceptors deployed on American soil: 40 at Fort Greely, Alaska, and four at Vandenberg Air Force Base, California. The Pentagon is also building a new missile field at Fort Greely and intends to add 20 more interceptors to the site by 2023 (US Department of Defense 2019a, 43). Since 2012, select Republican members of the House Armed Services Committee have strongly advocated for the construction of a third interceptor site on the East Coast (Stefanik 2018), although the commanders of the Missile Defense Agency and the Joint Functional Component Command for Integrated Missile Defense have stated that “there is no validated military requirement” to do so (US Department of Defense 2013). In June 2019, Undersecretary of Defense for Research and Engineering Michael D. Griffin suggested in a House Armed Services Committee memo that Fort Drum, New York, would be the preferred site because it “provides the best operational coverage,” despite it also being “the most expensive option with the most environmental challenges.” He was careful to note, however, that “since the Department’s 2019 Missile Defense Review determined there is no operational requirement for an East Coast [interceptor site], the Department has no intent to develop one” (US Department of Defense 2019b).
The GMD system relies on an extensive network of ground- and space-based sensors and radars, including launch detection satellites like Space-Based Infrared Sensors (SBIRS); the COBRA DANE radar at Shemya, Alaska; recently-upgraded early warning radars in California, the United Kingdom, and Greenland; forward-based X-band radars in Japan; Aegis Ballistic Missile Defense destroyers; and a sea-based X-band radar in the Pacific Ocean (US Department of Defense 2019a, 42). Additionally, Lockheed Martin’s construction of a new long-range discrimination radar began in September 2018, and is scheduled for deployment at Clear Air Force Station in Alaska in 2020 (Larter 2018). Meanwhile, as part of the Upgraded Early Warning Radar modernization program, the PAVE PAWS3 radars at Clear, Alaska and Cape Cod, Massachusetts, will be upgraded by 2023 (Keller 2018). The 2019 Missile Defense Review additionally notes that two new missile defense radars will be constructed in Hawaii and “in the Pacific region” by 2023 and 2025, respectively (US Department of Defense 2019a, 43–44). All of these sensors are highly vulnerable to interception.
Although Boeing, the prime contractor for GMD, describes the system as a “shield” (Boeing), its test record reveals that it is more likely to function as a sieve. Nearly half (20 out of 44) of the currently deployed GMD interceptors are fitted with the Capability Enhancement (CE)-I kill vehicle, which has only succeeded in two of its four interceptor tests (the most recent of which took place in 2008). Similarly, over a third of the interceptors (16 out of 44) are fitted with the CE-II kill vehicle, which also has a 50 percent testing record (Government Accountability Office 2019, 57). What’s more, according to the former head of the MDA, Admiral James Syring, these tests take place “in a controlled, scripted environment” (Syring 2013). Given these facts and figures, it seems highly unlikely that GMD would perform as advertised when faced with unexpected threats, decoys, and penetration aids, or multiple targets.
Decoys will pose significant challenges for the GMD system. In an exoatmospheric vacuum, heavy things and light things move the same way; therefore, differentiating decoys from reentry vehicles in space is incredibly difficult. This physics challenge is compounded by the fact that their lack of combat use means that the United States has little visibility into what other countries’ decoys look like. The enormous cost of each interceptor is also a significant factor. Utilizing a shoot-look-shoot firing doctrine may help limit the number of interceptors necessary to shoot down a single missile; however, in 2012 a National Research Council report suggested that “this approach is not adequately exploited in current US midcourse defense systems (such as GMD)” (National Research Council 2012, 103), with recent tests indicating that the MDA is instead experimenting with “double-tap” salvo launches, in which two interceptors are fired, and if the first makes a successful intercept, the second will target the “next most lethal object” (Panda 2019).
The MDA intended to replace the unreliable CE-Is as soon as possible by expediting the Redesigned Kill Vehicle program, which was scheduled for deployment between fiscal years 2023 and 2026. However, the GAO’s 2019 report to Congress on the state of US missile defense suggests that this program was accelerated too quickly because of “advancements in the North Korea missile threat.” As a result, “the program accepted too much risk,” causing significant technical delays and wasting an additional $600 million before eventually being canceled on May 24th (Government Accountability Office 2019, 60). The cancellation of the Redesigned Kill Vehicle leaves the GMD program a mess. GMD interceptors only have an initial service life of 20 years, which the 20 currently-deployed CE-Is will reach in the mid-2020s. With nothing scheduled to replace them, the GMD program could lose nearly half of its deployed interceptor arsenal in just over five years.
In late August 2019, the Missile Defense Agency issued a classified draft request for a Next Generation Interceptor to replace the Redesigned Kill Vehicle program; it remains unclear how this new interceptor will differ from the now-canceled one (McLeary 2019). The MDA is also exploring a “multi-object kill vehicle” as a next-generation kill vehicle, which would allow more than one kill vehicle to be launched from a single booster. The concept was originally canceled in 2009, but in 2015 the MDA awarded several contracts with an intention to develop the multi-object kill vehicle concept further (Missile Defense Agency 2016a, 5).
Regional missile defense
The US missile defense complex also includes several systems designed to defend against regional missile attacks. Many of these systems are mobile and can be surged to crisis zones in short periods of time. Some are also interoperable with other countries’ military assets, and can therefore be used for combined operations.
Terminal High Altitude Area Defense (THAAD)
The THAAD system is the only US missile defense system designed to intercept short-, medium-, and intermediate-range targets both inside and outside the atmosphere, during their terminal phase of flight. Similar to GMD, THAAD uses hit-to-kill technology. A typical THAAD battery has four primary components: 48 single-stage, solid fuel interceptors with separating kill vehicles (typically eight interceptors per launcher); six M1075 truck-mounted launchers; an AN/TPY-2 X-Band radar to track missiles up to 1,000 kilometers away; and a Tactical Fire Control and Communications unit that links the whole system together and networks it with external command and control nodes (Missile Defense Agency 2019b).
THAAD’s concept development began in 1989, but until 2006 its test record was very poor (only two successes from eight tests) (Syring 2014; Missile Defense Agency 2016b). Since 2006, however, THAAD has a perfect test record of 16 successful consecutive intercepts (Missile Defense Agency 2019a), including against an intermediate-range ballistic missile target in July 2017 and a test using a Remote Launcher Kit in August 2019 (Hughes 2019).
At the time of writing, the US Army owns seven THAAD batteries, many of which have been deployed abroad. There are long-term THAAD deployments in Guam and South Korea, the latter causing considerable regional controversy. Claiming that THAAD’s AN/TPY-2 radar could penetrate deep into Chinese territory, China launched a social and economic coercion campaign against South Korean businesses, with Chinese tourism to South Korea plummeting to new lows in 2017, costing the South Korean economy $6.5 billion in lost revenue (Kim and Blanchard 2017). The bitter dispute was characterized by China successfully flexing its soft-power muscles, even going so far as to task state-sanctioned teenage Chinese rappers to write viral, anti-THAAD rap songs (CD Rev 2017). In order to resolve the dispute, President Moon Jae-in promised Beijing to abide by the “Three Nos”: no new US missile defenses, no South Korean integration into a regional US missile defense system, and no trilateral military alliance with the United States and Japan, an extraordinary concession by a key US ally (Panda 2017). Many South Koreans were also angered by THAAD’s rapid deployment in 2016, and near-constant protests at the THAAD site’s entrance since then have forced the US military to use helicopters to transport supplies to and from the site (Choi, Chung, and Kim 2018).
THAAD’s relatively small footprint makes it particularly suitable for rapid and temporary deployments. In March 2019, US European Command deployed a THAAD battery to Israel for three weeks (Smith 2019), and from May to August 2019, the Army briefly deployed a THAAD battery to Romania while the nearby Aegis Ashore complex was undergoing a three-month upgrade (NATO 2019).
Additionally, the United Arab Emirates – THAAD’s first foreign customer – has purchased and deployed two THAAD batteries as part of an estimated $1.135 billion contract that included 48 interceptors, nine launchers, two radars, and THAAD operator/maintainer courses at Fort Bliss, Texas (the first 81-student Emirati cohort graduated in late 2015, the second cohort graduated in May 2016) (Biggers 2017). Saudi Arabia has also purchased 360 interceptors, 44 launchers, seven AN/TPY-2 radars, and 16 Tactical Fire Control and Communications units for $15 billion, with the contract expected to be completed in April 2026 (Cone 2019).
Over the coming years, the Army intends to make THAAD increasingly interoperable with the Patriot missile defense system. In theory, this would allow the shorter-range Patriot system to utilize THAAD’s long-range AN/TPY-2 radar for its own targeting purposes, thus vastly increasing its battlespace. According to Lockheed Martin, the key contractor for the integration, upon completion of the upgrade, the Army will also be able to launch the newly-developed PAC-3 Missile Segment Enhancement interceptors from a THAAD battery (Judson 2018). Lockheed is also developing an extended-range THAAD interceptor to intercept targets at three times the range of the current system; however, this is being developed at Lockheed’s own initiative, as the US government has not yet purchased the system (Freedberg 2017).
Aegis
The Aegis missile defense system is designed to intercept short-, medium-, and intermediate-range missiles during their midcourse and terminal phases of flight. It can be deployed both on land as an “Aegis Ashore” system, or at sea on Aegis ships – either Ticonderoga (CG-47) class cruisers or Arleigh Burke (DDG-51) class destroyers. Today, there are 38 operational Aegis ballistic missile defense–capable ships (five cruisers and 33 destroyers); however, 22 more destroyers are scheduled to be operational by fiscal year 2023 (US Department of Defense 2019a, 54). An Aegis ship is considered ballistic missile defense–capable if it is armed with ballistic missile defense interceptor missiles, and if its Aegis combat software has been modified to a particular variant – either the 3.6.X variant, the 4.0.3 variant, the 4.1 variant (also known as the Aegis Baseline 5.4 variant), the 5.0 Capability Upgrade variant (also known as the Baseline 9.1 variant), the 5.1 variant (also known as the Baseline 9.2 variant), or the 6.X variant (also known as the Baseline 10 variant) – that allows it to launch those missiles (Congressional Research Service 2019, 4).
The Aegis ballistic missile defense system uses three families of interceptor missiles: Raytheon’s Standard Missile-2 (SM-2) Block IV, the SM-6, and the SM-3. Both the SM-2 and SM-6 interceptors are designed for terminal intercept in the atmosphere, while the SM-3 is designed for exoatmospheric midcourse intercept.
The SM-2 was originally designed to intercept aircraft and anti-ship cruise missiles, but 75 of these were modified to create the SM-2 Block IV, which can intercept at higher altitudes using a blast fragmentation warhead, thus offering a terminal intercept capability against ballistic missiles (US Department of Defense 1999). The SM-2 Block IV has a perfect test record of four successes out of four attempts, with the most recent test in 2015 (Missile Defense Agency 2019a).
The SM-6 is the successor to the SM-2 and uses components of various other missiles, including the airframe of the SM-2 Block IV and the seeker from an AMRAAM air-to-air missile. The future variant of the SM-6 – the Block IB, which is scheduled for completion in 2024 – will replace the SM-2 airframe with a new one that includes a larger, 21-inch diameter rocket motor (similar to the SM-3 Block IIA), which should significantly increase its range and speed (Rogoway 2019). The SM-6 also possesses an anti-ship capability, demonstrated through a 2016 test that successfully struck a target on the ocean’s surface (Freedberg 2016). The SM-6 has a perfect test record of three successes out of three attempts, with the most recent test in 2017 (Missile Defense Agency 2019a). In August 2019, the Navy nearly doubled its SM-6 procurement objective to 2,331 missiles – a clear indication of the SM-6’s critical role for the Navy the coming decades (Shelbourne 2019).
Unlike the other interceptors in the Standard Missile family, the SM-3 uses hit-to-kill technology and is designed to intercept targets outside the atmosphere, during their midcourse phase of flight. The two current widely deployed versions of the SM-3 are the three-stage Block IA and Block IB. The Block IB has an improved seeker, signal processor, and throttleable divert and attitude control system, allowing it to adjust its course in mid-flight (Congressional Research Service 2019, 5). Full production of the Block IB was originally scheduled for the end of fiscal year 2012; however, the program has been plagued by technical issues, resulting in two test failures in 2016. Only after the Block IB completed a successful intercept in October 2017 was it given the green light for full production. In January 2018, however, additional technical issues with the throttleable divert and attitude control system were discovered, which further delayed production (Government Accountability Office 2019, 40–43). As a result, the program delivered only 12 of 36 planned SM-3 Block IB interceptors in fiscal year 2018 (Congressional Research Service 2019, 10). The MDA is apparently seeking to procure 204 SM-3 Block IB interceptors through 2023; however, the contract has not yet been finalized (Government Accountability Office 2019, 40–43).
The incoming Block IIA – developed in collaboration with Japan – has a 21-inch diameter airframe along its entire length (the Block IA and IB have 21-inch diameter boosters but are 13.5-inches in diameter along the rest of the airframe) (Congressional Research Service 2019, 5). This larger airframe, in conjunction with a faster burnout time, will increase the SM-3’s range and speed (the Block IIA travels at 4.5 kilometers per second, compared to the Block IA and IB’s 3 kilometers per second) (Butt and Postal 2011) and will facilitate the SM-3’s new mission of shooting down rudimentary ICBMs – a capability that the Missile Defense Agency will possibly test in 2020, as per the 2019 Missile Defense Review (US Department of Defense 2019a, 55). At the time of writing, the SM-3’s test record was 34 successful intercepts in 43 attempts, including tests conducted using Aegis Ashore and Japanese Aegis ships (Congressional Research Service 2019, 22–23). However, in January 2018, the SM-3 Block IIA failed an important intercept test (FTM-29) when the missile’s third-stage motor failed to ignite because of a faulty arm-fire device and the incorrect programming of the motor’s ignition sequence. After those technical issues were resolved, several high-level stakeholders – such as the Deputy Assistant Secretary of Defense for Developmental Test and Evaluation, Joint Functional Component Command Integrated Missile Defense, and Office of the Director, Operational Test and Evaluation – all lobbied for a complete re-do of FTM-29 to ensure that the interceptor would function as designed. The Missile Defense Agency opted instead for a scaled-back version of the test in order to keep the Block IIA program on schedule. This test was successfully conducted in October 2018 (Government Accountability Office 2019, 44–48). In August 2019, the US State Department approved the sale of up to 73 SM-3 Block IIA interceptors to Japan, on top of the 13 Block IIA and 64 Block IB interceptors already approved last year, amid rising tensions on the Korean Peninsula (The Defense Post 2019).
Phases I and II of the European Phased Adaptive Approach – an Obama-era plan for defending Europe from Iranian missile threats – have been completed, resulting in the forward-basing of four Aegis ballistic missile defense destroyers in Rota, Spain, the fielding of an AN/TPY-2 radar at Kรผrecik, Turkey, the establishment of a ballistic missile defense command center at Ramstein Air Base in Germany, and the establishment of an Aegis Ashore site at Deveselu, Romania.
Phase III – the establishment of an Aegis Ashore site at Redzikowo, Poland, and arming it with 24 SM-3 Block IIA missiles – has been pushed back and is now scheduled to be completed by May 2020. The construction of the Aegis Ashore site has been riddled with delays; the GAO’s 2019 annual report noted that the construction team “has failed to meet schedule milestones from the start of the contract,” and that “the contractor’s performance is still particularly poor in the areas of construction management, identification, procurement, timely delivery of important materials, and timely hiring of staff with appropriate skills.” According to the Missile Defense Agency, these delays will require a budget increase of at least $90 million (Government Accountability Office 2019, 38–39).
In March 2013, the Obama administration canceled a planned fourth phase of the European Phased Adaptive Approach, which would have introduced the SM-3 Block IIB to the Aegis program. The Block IIB was expected to travel at an improved velocity of 5–5.5 kilometers per second, which would have facilitated its mission of intercepting ICBMs in the early stages of flight, before the deployment of penetration aids or multiple warheads (Defense Science Board 2011, 9). However, the program was canceled because, in the words of a Defense Science Board Task Force, it would “require Herculean effort and is not realistically achievable, even under the most optimistic set of deployment, sensor capability, and missile technology assumptions” (Defense Science Board 2011, 33).
The SM-2, SM-3, SM-6, and other missiles – including the Tomahawk – can all be launched from Aegis ships using the Mk-41 Vertical Launching System. The Mk-41 VLS is a modular design that allows for some variation in missile configuration. The missiles are loaded into canisters (occasionally multiple missiles to a single canister), which are in turn loaded into the individual VLS cells. These cells are then organized into eight-cell “modules” (two rows of four), which share common exhaust systems.
Given that the Mk-41 system is also capable of launching Tomahawks, Russia has suggested that the Aegis Ashore deployments could have violated the Intermediate-Range Nuclear Forces (INF) Treaty when it still existed, which prohibited the deployment of ground-based missiles with ranges of 500 to 5,500 kilometers. However, the United States has continuously stated that the Mk-41 launchers deployed in Europe lack the “software, fire control hardware, support equipment, and other infrastructure needed” to launch Tomahawks. “Although it utilizes some of the same structural components as the sea-based Mk-41 Vertical Launch System installed on ships, the Aegis Ashore vertical launching system is NOT the same launcher as the sea-based MK-41 Vertical Launch System” (US Department of State 2017). Additionally, Article VII, paragraph 7 of the INF Treaty states that in order for a launcher to be considered in violation of the treaty, it must actually conduct a ground launch of a prohibited missile (US Department of State 1987). Since this never happened while the INF Treaty was in force, the Mk-41 Vertical Launch System launchers were not technically in violation.
This being said, the SM-3 Block IIA is likely to have a detrimental effect on arms control. In February 2019, James Miller, a former undersecretary of defense for policy during the Obama administration, said that “to bring the SM-3 IIA missile into the national defense architecture…means that China and Russia must expect the United States by 2025–2030 to have many hundreds of available interceptors for national missile defense. We should expect the Chinese nuclear arsenal to grow substantially and Russia to resist reductions below the 2010 New Strategic Arms Reduction Treaty – and to prepare seriously to break out” (Reif 2019b).
Patriot Advanced Capability-3 (PAC-3)
The PAC-3 is a single-stage, solid-propellant, hit-to-kill air and missile defense system designed to intercept short- and medium-range ballistic missiles during their terminal phase of flight. Because it intercepts at lower altitudes than THAAD – the other US terminal ballistic missile defense system – it is also able to shoot down aircraft.
A typical mobile Patriot battery consists of an AN/MPQ-53/65 phased array radar set, an AN/MSQ-104 Engagement Control Station, an EPP-III Diesel-Electric Power Plant, an OE-349 Antenna Mast Group, and an M901 Launching Station containing 16 interceptors, arranged into four “quad-packs” of four missiles. The United States currently owns and operates 60 Patriot batteries (US Department of Defense 2019a, 51).
The newly-developed PAC-3 Missile Segment Enhancement (MSE) includes a larger fins, upgraded actuators and thermal batteries, and a larger solid-propellant rocket motor, which increases the missile’s range. A PAC-3 launcher can accommodate 12 individual MSEs, or a combination of six MSEs and eight PAC-3s (two “quad-packs”) (Lockheed Martin 2015).
Of all the US missile defense systems, Patriot has seen the most combat use by far, having been used extensively during the 1991 and 2001 Iraq wars. However, its intercept record during those conflicts was abysmal. During the 1991 Gulf War, it was publicly reported that Patriot successfully intercepted 45 out of 47 Scuds; however, it was later discovered that the Patriot software designated a successful intercept whenever the interceptor detonated in the vicinity of the Scud, regardless of whether the missile was actually destroyed (Bin, Hill, and Jones 1998, 101). As a result, the Pentagon later downgraded the near-perfect intercept rate to 50 percent success, and the Congressional Research Service additionally noted that if Pentagon had applied their assessment methodology consistently, the intercept rate would in reality be much lower (Hildreth 1992). A later House Committee on Government Investigations report suggested that “there is little evidence to prove that the Patriot hit more than a few Scud missiles launched by Iraq during the Gulf War, and there are some doubts about even these engagements” (House Committee on Government Operations 1992, 179–188). Although Patriot is celebrated for its perfect success record during the 2003 Iraq War, the exact numbers remain classified; as such, these prior inconsistencies with both performance and assessment methodology – in addition to its failure to intercept rudimentary Houthi missiles in 2018 – raise concerns over the accuracy of this claimed success record (Lewis 2018).
Patriot has been – and continues to be – exported and deployed across the globe, to Bahrain, Germany, Greece, Israel, Japan, Kuwait, the Netherlands, Poland, Qatar, Romania, Saudi Arabia, South Korea, Spain, Sweden, Taiwan, and the United Arab Emirates (Werber 2019).
2019 Missile Defense Review
The Trump administration’s 2019 Missile Defense Review suggests that “[m]issile defenses provide US leaders a position of strength from which to engage potential adversaries diplomatically in peacetime or crises” (US Department of Defense 2019a, 28). This description suggests that missile defenses are not purely defensive systems, but offensive enablers that empower their owner to engage in more aggressive behavior.
An oft-repeated claim in the Missile Defense Review is that “missile defenses are stabilizing,” as they offer “the ability to prevent or limit damage from an adversary offensive missile strike” (US Department of Defense 2019a, 29). However, this argument is a misinterpretation of basic deterrence theory, which states that damage limitation can actually destabilize the arms race, because countries will attempt to build offensive systems to offset their adversary’s defensive systems. This dynamic is currently on display with Russia and China, both of which are hard at work developing capabilities that are specifically designed to counter US missile defenses.
The Trump administration’s Missile Defense Review has significantly worsened this security dilemma. By specifically referencing Russia’s and China’s evolving missile arsenal – and declaring that the United States will seek to detect and destroy “any type of target,” “anywhere, anytime, anyplace,” either “before or after launch” (The White House 2017) – the United States can no longer claim that “[e]nhanced missile defense is not intended to undermine strategic stability or disrupt longstanding strategic relationships with Russia or China,” as is written in the 2017 National Security Strategy (President of the United States 2017, 8).
The Missile Defense Review also notes that the United States “will not accept any limitation or constraint on the development or deployment of missile defense capabilities needed to protect the homeland against rogue missile threats” (US Department of Defense 2019a, 31). This statement diverges somewhat from previous administrations, which emphasized that the missile defense system was designed to specifically defend against select adversaries, and not to undermine strategic nuclear deterrence. And it is precisely what drives Russian and Chinese countermeasures, which are based on the assumptions that unconstrained and technologically advanced US missile defenses will eventually be capable of disrupting their strategic retaliatory capability and could be used to strengthen an offensive US war-fighting posture.
To support this new “no-limits” policy on US missile defense, the Missile Defense Review directs the Missile Defense Agency to consider developing and fielding a variety of new capabilities for detecting and intercepting missiles either immediately before or after an adversarial missile launch. This includes developing a defensive layer of space-based sensors (and potentially interceptors), a new or modified interceptor for the F-35 fighter-jet, and lasers mounted on drones, all of which would theoretically be used to attempt boost-phase intercept, despite the fact that the National Academy of Sciences clearly states that “boost-phase missile defense – whether kinetic or directed energy, and whether based on land, sea, air, or in space – is not practical or feasible” (National Research Council 2012, 65).
This point has been driven home by the Pentagon’s recent decision to indefinitely postpone all work on neutral particle beams, only six months after they declared their intention to test one by 2023. In September 2019, Undersecretary of Defense for Research and Engineering Michael Griffin acknowledged that the technology is “just not near-term enough” (Tucker 2019).
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