An Analysis of the 2019 Missile Defense Review

A Patriot launcher unit equipped with PAC-2 missiles deployed in Turkey.

The 2019 Missile Defense Review (MDR), a policy document outlining the way forward for American missile defense efforts, was released in January 2019 after years of work. The MDR’s contents should not surprise anyone who has been following American missile defense for the past few years, as it largely reiterates existing policies, albeit with a few curveballs. On many of the more contentious policy items, the MDR punts by calling for further investigations to be completed within six months after the publication of the MDR itself. Nonetheless, the document represents the DoD’s most comprehensive enumeration of missile defense policy in many years and will be widely read by lawmakers, defense industry watchers, and analysts of various stripes. This article — by no means exhaustive — will cover some of the more noteworthy statements (and omissions) contained in the MDR, drawing connections to wider issues and trends in missile defense.

Why missile defense?

Arleigh Burke-class Aegis BMD destroyer USS Hopper fires an SM-3 during a test.

Oftentimes, discussions of missile defense focus on technical facets rather than strategic and conceptual ones. Much has been written by the DoD, contractors, and researchers on how to best intercept missiles, but discussions of why missile defense is necessary, who it should be directed against, and how high of a priority it should be are more rare.

This is one gap that the MDR addresses by laying out a number of tangible reasons why missile defense is worth tens of billions in yearly expenditures. First and foremost is — unsurprisingly — the threat posed by North Korea and Iran, which are both mentioned explicitly throughout the document. Because there are hundreds of articles on missile defense vs. the so-called “rogue states,” and because the MDR does not really add anything novel on this subject, I will not focus on North Korea and Iran in this article. That does not, however, mean these threats are de-emphasized in the MDR itself.

A mockup of a North Korean Unha-9 rocket, which shares many parts with the Taepodong-2 technology demonstrator.

More interesting are the various ways in which the MDR supplements the prevailing “develop missile defenses against North Korea and Iran” narrative. Indeed, based on the MDR, one could infer that the Trump administration (and perhaps the national security establishment more broadly) would continue to actively pursue missile defense even if “rogue state” threats did not exist.

One example is a sentence remarking that “the intentions of potential adversaries can change directions unexpectedly and more rapidly than we can develop and field defensive capabilities” (8). To be sure, this is aimed primarily at North Korea, which often feigns interest in denuclearization and arms control only to quickly renege. Were the US to remove its missile defenses from the region as part of an agreement, North Korea could change tack and launch an attack before redeployment of the assets would be possible. However, it also reflects the uncertainty inherent in missile proliferation and the fact that the threat picture often evolves more rapidly than new defenses can be developed and fielded. Regimes can change (relatively) quickly, and states like North Korea could sell missiles or transfer technology to unsavory actors. Missile defense systems take decades to develop, test, and field; since it is hard to know exactly what the threat picture will look like in 2040 and beyond, the MDR argues for a high level of investment as a hedge.

Later on, the MDR includes a quote from Colin S. Gray, a prominent strategic studies scholar. It reads, “U.S. missile defence can critically reduce an attacker’s confidence in the prospects for success in its offensive strike planning. Given the inherent and irreducible uncertainties of war that should fuel doubt in such plans, the additional uncertainty imposed by U.S. missile defence should prove decisively deterring in the attacker’s calculations” (25). This relatively simple but nonetheless important insight helps address one of the most common critiques leveled at missile defenses, namely that the interceptor systems have relatively low interception success rates. This complaint is mainly applicable to the GBI and the SM-3, since Patriot and THAAD have impressive test records (and Patriot has been used extensively in combat).

Gray’s quote highlights that missile defenses (especially those of a strategic nature) serve primarily as deterrence. And when it comes to deterrence, missile defenses do not need to be completely airtight — even the imperfect interceptors currently deployed are reliable enough that an adversary would be unlikely to test them with a first strike.

Another segment in the MDR touts the utility of missile defenses vs. an accidental/unintended/limited attack. This category includes scenarios such as a rogue actor getting hold of a long-range missile and firing it or a collapsing regime launching a handful of weapons as a parting blow. Under these circumstances, America’s own strategic weapons would lose their deterrent value, as targeting the handful of responsible persons with a nuclear weapon would present an ethical quandary. Homeland missile defenses, however, would help discourage such attacks by rendering them unlikely to succeed and, if this deterrent fails, would stand a good chance of neutralizing the offending missiles. In this capacity, homeland missile defenses could help avert a nuclear catastrophe — imagine a scenario in which five Russian ICBMs were launched at major American population centers due to some sort of a malfunction. Without missile defenses, there would be a strong incentive to launch some sort of counterattack, which could quickly escalate into a full-scale exchange, as neither party wants to lose their weapons on the ground. With homeland defenses, the US could instead intercept the missiles and verify that the launch had been accidental. This is an often-overlooked benefit of homeland missile defenses but one that could acquire increased saliency as nuclear weapons and ballistic missiles continue to proliferate.

The insights presented above are not groundbreaking, but the MDR is intended for policymakers and laypeople in addition to defense insiders and game theory wonks. Hopefully, the inclusion of these lesser-discussed benefits of missile defense in the MDR will help inform the ongoing debate surrounding homeland defenses.

SM-3 clarity

An SM-3 ballistic missile interceptor launches from a Ticonderoga-class cruiser.

One miscellaneous matter of policy clarified by the MDR is the role of the SM-3 Block IIA interceptor, which has been recognized for years as possessing a latent strategic capability that has not been widely discussed or tested. The MDR states that the Block IIA has the capability to “provide an important ‘underlay’ to existing GBIs for added protection against ICBM threats to the homeland.” As expected, this confirms that the SM-3 Block IIA could not replace the GBI but rather will form a sort of inner defensive layer. How exactly this would manifest in the doctrine is still unclear. Would the addition of the SM-3 Block IIA reduce the number of GBIs initially fired at an incoming target? Would Block IIAs be used exclusively when the initial GBIs fail to intercept or would they be launched in tandem with GBIs against every target? How exactly the SM-3 Block IIA is employed will have a substantial impact on the deterrence equation.

The MDR also addresses, but does not definitively answer, the question of platforms: “[T]his new [Block IIA] underlay capability will be surged in a crisis or conflict to further thicken defensive capabilities for the U.S. homeland. Land-based sites in the United States with this SM-3 Blk IIA missile could also be pursued” (55). Because “surged” implies a mobile launch platform, this section clearly places the onus for providing SM-3 underlay capability on the US Navy, at least in the near-term. Of course, this is the only option for near-term SM-3 Block IIA deployment, but it will nonetheless irk the Navy, which has repeatedly expressed its annoyance at having to supply so many combatants for the missile defense mission. When to surge will be an issue in and of itself; tensions on the Korean Peninsula are never particularly “low,” so there will be a constant tradeoff between the desire to have underlay in case conflict breaks out and the need for Aegis BMD ships in other places. The argument for land-based SM-3 Block IIAs is certainly compelling, although constructing the launch sites would take time. In the short term, the existing Aegis Ashore test site in Hawaii may be converted to give the islands better coverage, but this would have no bearing on the CONUS situation.

Russia and China

Type 052 destroyer Qingdao receives a warm welcome at Pearl Harbor.

The MDR states that current strategic efforts are not directed at Russia and China, though it mentions them as a target of regional defenses. This is in line with past US policy and the actual capabilities of the homeland defense network, which lacks both the number of interceptors and the technical sophistication needed to thwart a Russian or Chinese attack.

Nonetheless, the MDR will not do much to assuage the fears of Russia and China because it does not give any assurances that strategic defenses will not threaten Russian and Chinese deterrent in the future. The section concerning Russian and Chinese strategic capabilities reads, “The United States relies on nuclear deterrence to prevent potential Russian or Chinese nuclear attacks employing their large and technically sophisticated intercontinental missile system” (8). Nowhere does the MDR explicitly state that the US wishes to preserve mutually assured destruction. Rather, it seems to imply that American defenses are simply not yet up to the task of countering Russian and Chinese attacks. This raises the following question: if a defensive system capable of seriously mitigating a Russian or Chinese attack were to be feasible, would the US deploy it? And what if, after a decade or two of further North Korean missile development and stockpiling, overmatch against “rogue states” begins to encroach upon Chinese deterrent? Furthermore, the MDR states that the US “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.” This suggests that the only recourse available to Russia and China is to enhance their offensive capabilities and risk precipitating an arms race.

Keeping in line with its refusal to accept constraints on missile defense, the MDR dismisses contemporary Russian and Chinese protests as unfounded. One section reads, “For example, in 2001, when the United States announced its withdrawal from the 1972 AntiBallistic Missile (ABM) Treaty to facilitate the U.S. deployment of homeland defense against rogue state missile threats, Russian President Putin explicitly said: ‘This step has not come as a surprise to us…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.'” Basically, the authors state here that past administrations’ acquiescence renders current objections invalid. This is not the most compelling argument — since the American withdrawal from ABM, missile defenses have improved substantially in capability, and a spate of new systems could take the homeland defense network quite a bit past the handful of GBIs originally envisioned when the US withdrew.

Future technologies

A US Navy Laser Weapons System Demonstrator.

This brings us to the final issue: America’s medium and long-term goals for missile defense. On this front, the MDR is quite bullish, recommending further investment in a number of technologies which have been trialed in the past but proved unfeasible.

One approach of longstanding interest to the military, “kinetic or directed-energy boost-phase defenses,” (30) is mentioned. Boost phase interception is attractive insofar as it destroys the missile before decoys and MIRV warheads can be deployed, but positioning assets so that the target can be engaged within the short boost timeframe requires loitering close to probable launch sites and thus exposes the interception platform itself to destruction in the opening phase of a conflict.

One solution envisioned by the MDR is that of space-based interceptors. This approach has been studied extensively, with virtually all third-party assessments emphasizing the astronomical costs and relatively unimpressive benefits of a satellite-based interception system. Yet, the DoD has been adamant that the matter deserves further attention, suggesting that perhaps the military’s plans do not correspond exactly to what has been envisioned by outside analysts.

Were space basing to be successfully implemented — and protected from anti-satellite weapons, which is a concern — the benefits would be substantial. Most obviously, hostile missiles could be engaged regardless of their launch site, whereas current land-based systems have a limited engagement envelope and must be correctly positioned. Any space-based system would likely be a boost-phase system as well, so MIRVs and decoys would be negated.

The main issue raised with this approach is that persistent coverage would require an exorbitant number of LEO satellites, each of which would only deploy a few interceptors. So, though the constellation would be persistent, its magazine depth would be poor. One solution to this, as mentioned in a 2018 Defense News interview, is using directed energy weapons (DEWs) aboard the satellites rather than kinetic interceptors. Accomplishing this would be a herculean technological feat, as the DEW would have to be immensely powerful and quite compact. Efforts on this front have been underway for decades, and the MDA is currently funding research into compact, megawatt-class lasers for potential employment in a high-altitude UAV. Two approaches, a diode-pumped alkali laser and a fiber-combining laser, are being examined, although both have quite a long way to go before they could be deployed aerially. The President’s 2020 Budget will further elaborate on how the DoD wishes to structure its future DEW investments. At the moment, it is unclear if laser-based boost phase defenses will ever be feasible, but the hypothetical benefits of such a system are tantalizing enough to keep the R&D efforts plodding along.

If the US were able to field a space-based missile defense system, Russia and China would undoubtedly protest, and not without reason — in the aforementioned Defense News interview, Michael Griffin (undersecretary of defense for research and engineering) noted that the benefits of a space system would be not against the “first missile, but . . . the second missile, [] the fourth missile, the 16th and the 350th missile that comes at the U.S.” Of course, Russia and China are the ones with 350 strategic missiles, not North Korea and Iran. This comment, probably made offhand, is emblematic of a broader issue: many American officials either do not realize that their missile defense aspirations threaten Russian and Chinese deterrent or simply do not care.

Another interesting tidbid relates to cruise missiles, which are often ignored in discussions of missile defense (including my own) but have continued to rapidly improve and proliferate. The original MDR text summarizes the anti-cruise-missile roadmap quite well:

NORAD has a three-phase program to strengthen the defense of North America against cruise missiles. Under the first phase now underway, NORAD is improving defensive coverage of the National Capital Region (NCR) by incorporating advanced sensors into the existing architecture. In Phase 2, also underway, NORAD is expanding surveillance capabilities around the NCR. Phase 3, which is in the early planning stages, will incorporate emerging technology and explore new options to expand surveillance and tracking of cruise missiles for the rest of North America. In addition, NORAD and the U.S. Air Force are upgrading aircraft that monitor the U.S. airspace with new sensors capable of tracking and targeting challenging offensive air threats like advanced cruise missiles (45).


Having addressed what the MDR does talk about, it is worth considering the omissions. Or, more accurately, the deferments. Eleven issues in total are consigned to future reports rather than being directly addressed by the MDR. These include upgrading all Aegis destroyers with BMD capability, enhancing discrimination and tracking, and investigating the potential of space-based sensors and weapons. These are some of the most important issues facing American missile defense, so it is unsurprising that they require separate reports which will probably be classified (at least in portion).

And, of course, the actual impact of the MDR will depend on a number of factors, including whether Congress funds the systems it calls for and whether its proclamations become enduring aspects of US policy. With regards to the former, the Democratic House will probably be looking to reduce military spending, although missile defense tends to enjoy bipartisan support and may be able to escape the brunt of the cuts. Concerning the latter, the MDR is probably one of the Trump administration’s least-controversial policy documents, so there is no reason to believe its precepts will be left in the ditch by future administrations.

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