Although China, Russia, and the United States have together experienced numerous crises and tensions since the end of the Cold War, one important reason that each state has refrained from employing military force directly against the others is their robust nuclear deterrents and survivable “second-strike” capabilities—their assured ability to retaliate effectively with their own nuclear forces even if they were attacked first. Furthermore, US extended nuclear security guarantees—Washington’s promise to protect its allies against nuclear threats with nuclear forces, if necessary—has dissuaded other potential nuclear weapons states, namely Japan and South Korea, from pursuing their own nuclear weapons capability. Despite doubts, these countries have continued to place their faith in Washington’s will and capacity to defend them against North Korea and other threats. However, new military technologies such as missile defenses, anti-satellite weapons, and hypersonic missile systems, could raise the risks of nuclear weapons use in future crises, especially if accompanied by certain risk-acceptant operational concepts. Ballistic missile defense (BMD) systems may convince their possessors that they could launch a disarming first strike—expecting their missile shields to protect them against any retaliatory strikes. Hypersonic delivery systems present new challenges for crisis stability due to their rapid speed and unpredictable flight paths. Furthermore, states have incentives to use cyber weapons early in a conflict to exploit any vulnerabilities of their opponent before their own can be neutralized by an enemy. States may even consider launching their nuclear forces before they have been attacked, such as on warning of an assault despite the risks of misperception and miscalculation.
Chinese and Russian officials have already complained about the allegedly disruptive nature of the expanding US capabilities for missile defense, precision strikes, and other strategic technologies. The strong US offensive capabilities, both nuclear and conventional, exacerbate these concerns since they increase its potential for successfully pre-empting Chinese and Russian nuclear missiles before they have been launched.2 Experts believe that the Chinese share Russian concerns about “conventional counterforce” – US preemptive attacks using non-nuclear hypersonic weapons or even cruise missiles against the PLA’s nuclear forces and command nodes and then using missile defenses to defeat any ragged Chinese counterstrike. Both countries are seeking to overcome US offensive and defensive capabilities by actively researching all these new strategic technologies for possible military application.
It is important not to exaggerate the potential for near-term technological breakthroughs in these capabilities. By their very nature, however, the pace and impact of these novel military weapons based on revolutionary capabilities are hard to predict. Few existing treaties explicitly constrain the quantitative or qualitative dimensions of these new strategic technologies. The best time to negotiate arms control agreements limiting the development of potentially destabilizing systems is before the weapons are deployed, but there are major impediments to progress in this area.
THAAD as Symptom
During the past year, the focus of the Russia-China-US strategic weapons dispute in Asia has been the possible deployment of a US-made Terminal High Altitude Area Defense (THAAD) system in the ROK. The THAAD has a longer range, better sensors, and is, in general, more capable than the existing or planned South Korean BMD systems. Until now, the ROK Ministry of National Defense has reacted to the North Korean missile threat by developing an indigenous BMD program for intercepting short- to medium-range ballistic missiles using primarily Patriot-type interceptors as well as preemptive strikes with the ROK’s own missiles and warplanes. Seoul and Washington have not held any formal talks on a possible THAAD deployment in South Korea.3 However, the ROK media has run many stories asserting that South Korea might host US-operated THAAD batteries or buy them for the ROK’s own armed forces.4
Despite its historical close defense ties with Washington, Seoul has declined to join the missile defense architecture that the United States is constructing in the Asia-Pacific region. Unlike Japan, South Korea is not sharing, let alone co-developing, its BMD technologies with other countries or hosting radars that could help defend the United States from a long-range ballistic missile attack. Even the US BMD radars and PAC-3 interceptors deployed in South Korea are officially intended only to defend the ROK and the US troops stationed there. Furthermore, the ROK considers the planned US global missile defense network as too expensive and elaborate for Seoul’s needs, since North Korea can strike the South with other types of systems, such as long-range artillery and special operations forces.5 In addition, Russian and especially Chinese officials have publicly demanded that Seoul not deploy THAAD, claiming that such a system in South Korea could threaten their nuclear deterrents and exacerbate regional tensions, particularly regarding North Korea.6 A more recent ROK concern is that yielding to Beijing on THAAD could encourage further Chinese pressure on South Korea and weaken the US-ROK alliance.7
Some South Korean and US analysts, however, believe that THAAD would improve ROK defenses against North Korea, promote alliance solidarity, and advance other joint ROK-US objectives.8 For example, the radar data from a ROK-based THAAD, if shared with the Pentagon and its partners, could enhance offshore US and Japanese BMD capabilities since interlocking sensors can better identify, track, and discriminate among missile targets. The redundancy would also help safeguard against the potential loss of some sensors due to technological shortcomings or hostile action.
The 2010 “Ballistic Missile Defense Review” states, “[t]oday, only Russia and China have the capability to conduct a large-scale ballistic missile attack on the territory of the United States, but this is very unlikely and not the focus of U.S. BMD.” Yet, it acknowledges that, “[b]oth Russia and China have repeatedly expressed concerns that U.S. missile defenses adversely affect their own strategic capabilities and interests.”9 Beijing and Moscow have become even more vocal in their opposition, e.g., in March 2013, President Xi Jinping and President Vladimir Putin issued a joint statement opposing any “country or group of countries unilaterally and unlimitedly strengthening missile defenses” and thereby “harming strategic stability and international security.” They instead called on countries “to confront the proliferation of ballistic missiles within the framework of international law and political diplomacy, where the security of one group of nations cannot be sacrificed at the expense of another group of nations.”10 In their view, an effective missile shield could encourage Washington to intervene militarily in other countries regardless of Chinese and Russian objections. At the 2007 Munich Security Conference, Putin explicitly warned that, unless deterred by Russia’s nuclear forces, the US military “hyperpower” would be free to impose its unilateral will on other countries without fear of effective military retaliation.11 Chinese experts also depict US BMD efforts as designed to place Beijing at a strategic disadvantage by undermining a key source of its power.12 Additionally, Chinese and Russian policy makers worry that US missile defense cooperation with countries on their periphery could embolden their neighbors in territorial and other disputes and, more generally, weaken their regional influence.
Yet, both China and Russia have been acquiring surface-to-air missiles that have some capacity to shoot down low-flying ballistic missiles. Furthermore, they have been researching more advanced BMD systems, possibly simply to better understand these technologies in order to better overcome US missile defenses, or potentially to deploy their own BMD systems. China may want to counter India’s progress in developing long-range nuclear-armed missiles, whose increasing range has made all Chinese territory vulnerable to an Indian missile strike.13
The effects of potentially disruptive strategic technologies extend well beyond Asia. China, Russia, and the United States are all developing counter-space capabilities that can be used for military purposes against orbiting satellites and other targets in outer space. Indeed, any system that can track and intercept a ballistic missile in mid-flight could also be used to target low orbiting satellites, whose trajectory is more predictable and whose countermeasures are normally weaker. Modern militaries are highly dependent on these space-based enablers, as they use space assets for reconnaissance, navigation, targeting, and intelligence-gathering. These assets are essential for conducting military operations, verifying arms control agreements, analyzing foreign defense developments, providing early warning of foreign missile launches, and monitoring long-term environmental conditions. Even commercial satellites make important military contributions in the form of communications, imagery, and weather forecasting.
As the United States and Soviet Union developed satellite technologies during the Cold War, concerns arose over the use of anti-satellite weapons (ASAT) to damage or destroy space-based assets. The Soviet Union developed and operationally deployed an ASAT, while the United States tested kinetic kill vehicles and other ASAT technologies. Both countries eventually agreed on a moratorium on ASAT tests, though not research, in the 1980s due to their mutual reliance on satellites for a range of military and civilian purposes.14 China conducted its first known ASAT test in 2007, when the PLA used a ground-based, medium-range ballistic missile to launch a direct-ascent ASAT system, the SC-19, to destroy an obsolete Chinese weather satellite, the Fengyun-1C, by colliding with it. The SC-19 has a reported range of between 1,000 and 1,500 kilometers, which makes it a threat to low-orbit satellites.15 But the uproar that followed the incident, which broke the moratorium on ASAT tests and generated thousands of pieces of space debris, has led Beijing to keep its subsequent ASAT research low-key.16
In recent years, China has sought to downplay international objections by describing its ASAT activities as designed to research BMD technologies akin to those the United States has been testing. Since January 2012, the PLA has conducted several declared BMD tests, though the United States has publicly characterized at least the third test in January 2013 as designed to attack satellites rather than missiles.17 The system used in these recent Chinese tests is the SC-19, though China has avoided generating debris by testing the system against particular locations in space rather than actual satellites.18 US defense officials believe that in May 2013 China successfully tested a high-altitude rocket capable of carrying an ASAT more than 10,000 kilometers above the earth’s surface,19 and it is among the states researching ground-based directed-energy weapons for neutralizing satellites by damaging their sensors and other components.
Although the PRC government only confirms its interest in testing BMD technologies, Yue Gang, a retired colonel in the PLA General Staff Department, has acknowledged that China’s “anti-satellite and missile defense technologies have steadily improved.”20 The main ASAT target would be the United States, but the Japanese government has also been pursuing the military application of outer space. Since 2012, the Japan Aerospace Exploration Agency (JAXA) has been legally permitted to engage in military space activities, to include developing advanced surveillance satellites and other dual-use technologies with potential military as well as civilian applications. In December 2013, Japan’s first National Security Strategy described the importance of developing national space capabilities. In April 2015, the Office of National Space Policy, citing threats from Chinese activities, released a detailed plan to augment the country’s capabilities for space-based reconnaissance and missile early warning over the next decade.21
The United States has welcomed Japan’s new approach as a means of augmenting the already powerful US space capabilities, which include counter-space weapons, as demonstrated in February 2008, when the US Navy used a ship-launched SM-3 interceptor, designed to attack ballistic missiles, to destroy a non-responsive USA-193 satellite. “Operation Burnt Frost” demonstrated that the United States could successfully hit a satellite at 240 kilometers above sea level.22 The US government described the test as an exceptional response to the impending crash of a failing satellite carrying a dangerous propellant.23 But Chinese, Russian, and other analysts interpreted the interception, which occurred a little more than a year following the Chinese ASAT test, as a warning to Beijing and others that the United States retained retaliatory ASAT capabilities. Indeed, in February 2015, the head of U.S. Strategic Command, Admiral Cecil D. Haney, asserted, “To effectively deter adversaries — and potential adversaries — from threatening our space capabilities, we must also understand their capabilities and their intent and make it clear that no adversary will gain the advantage they seek by attacking us in space.”24
Russia also presumably has counter-space capabilities inherited from former Soviet programs, such as the Naryad-VN and Naryad-VR systems, which were developed in the late 1980s but never deployed due to the Russian moratorium on further ASAT testing.25 Newer Russian surface-to-air systems such as the S-400 and S-500 could be fitted with direct-ascent ASAT weapons. In March 2009, in reference to Chinese and American ASAT capabilities, Deputy Minister of Defense Vladimir Popovkin confirmed that “similar works are done in Russia too.” adding that Russia will need ASAT capabilities in the event someone puts weapons in space.26 The 1967 Outer Space Treaty prohibits such deployments, but Chinese and Russian officials often describe even unarmed US space-based missile interceptors, which destroy targets through “hit-to-kill” technologies, as space weapons.27
Hypersonic Delivery Systems
China, Russia, and the United States are all researching, developing, and testing delivery systems that can achieve hypersonic speed—defined as flying at least five times the speed of sound (Mach 5, or more than 6,125 kilometers per hour). Each seeks at least a small arsenal of hypersonic weapons as niche capabilities, though they have different intentions.28 None of them has yet committed to deploying an operational system due to their continuing technical challenges and high financial costs, but they all aim to achieve this capability. Ongoing scientific and technical developments of new materials, fuels, manufacturing processes, and artificial intelligence systems could make it easier to develop effective hypersonic delivery systems in the future.29
The United States launched the first research and development program for hypersonic weapons more than a decade ago as part of a loosely defined Department of Defense initiative known as Conventional Prompt Global Strike. The Pentagon has spent about $1 billion on research, but several more billions will be needed to build and deploy operational hypersonic weapons.30 The United States has sought to develop a conventionally-armed delivery system that could strike transient mobile targets (such as terrorists who had acquired a nuclear weapon or mobile missile launchers) whose location might be known for only a brief time or for use against deeply buried and hardened targets, such as WMD storage facilities.31 The initial efforts explored simply placing conventional warheads on intercontinental ballistic missiles (ICBMs) and relying on the force of their kinetic impact to destroy a target without the fallout of a nuclear detonation. Current research focuses on the Advanced Hypersonic Weapon (AHW) long-range glide vehicle and the X-51 “Waverider” scramjet-powered vehicle. The systems are not expected to become operational weapons, but they may provide insights needed to develop one by the end of the next decade.
The AHW is a ground-based hypersonic glide vehicle (HGV) that, rather than arching upwards into space as a typical projectile would, is shot on a rocket at a trajectory so low that it barely exits the atmosphere before detaching from the booster and plummeting to earth on a horizontal trajectory at hypersonic speeds. Due to their maneuverability, low altitude, and flat trajectory, HGVs present different challenges for a defender than strategic ballistic missiles, which fly through space in more predictable ballistic trajectories before descending toward a target from space.32 The first US AHW test in November 2011 successfully hit a target more than 3,700 kilometers away in 30 minutes with a non-ballistic glide trajectory sufficiently distinct from that of an ICBM, helping to identify its non-nuclear nature.33 In contrast, the X-51 WaveRider is an air-launched hypersonic cruise missile delivered by a small rocket that upon release is powered by a supersonic combustion ram jet, or scramjet, at Mach 5 or higher.34 The X-51 reached a record speed of Mach 5.1 in a May 2013 test, but has experienced numerous failures that make the system currently impractical for deployment.
Having hypersonic weapons with global reach would enable even US-based systems to strike time-sensitive, high-value targets throughout the world in less than an hour. The capability would make the United States less reliant on overseas-based systems, less dependent on foreign permission to use a system, and less concerned by anti-access or area-denial (A2/AD) threats.35 In Asia, the United States has conventional strike systems based in South Korea and Japan, but the Pentagon needs host-nation approval to use these weapons. The United States can also employ aircraft carriers as well as strategic bombers flown from the United States, but these planes and ships can take time to maneuver into position and are vulnerable to preemptive attacks and enemy air defenses. However, arms control advocates believe that both types of systems present problems for crisis stability. Whereas conventionally armed ballistic missiles can be misinterpreted as nuclear-armed ICBMs, hypersonic glide vehicles are more difficult to track since they are not flying a ballistic flight path but are maneuvering at high speeds and flying too low for conventional radars. Russia and China might detect their launch but then they might vanish from their radars until they landed somewhere.36
Russian analysts have warned that hypersonic systems could give the United States the ability to rapidly destroy Russia’s nuclear deterrent and command and control assets. Putin has cautioned that US high-speed, high-precision, long-range strike systems “could negate all previous agreements on the limitation and reduction of strategic nuclear weapons, thereby disrupting the strategic balance of power.”37 In Putin’s view, unless confronted by a powerful Russian nuclear deterrent, the United States would be tempted to launch a preemptive first strike with these weapons.38 Russian experts argue that these capabilities would make it harder to establish a strategic balance, ensure an adequate deterrent capacity, and negotiate stabilizing and balanced strategic arms control agreements.39 They have also warned that systems using long-range missiles could increase the risk of misperceptions and accidental wars since Russian leaders would not know whether US weapons flying in Russia’s direction were actually intended for targets outside Russian territory.40 Russian leaders argue that they would feel greater pressure to launch their nuclear strike before Russian strategic forces, including their command and control (leading to “decapitation”), were preemptively destroyed by a sudden US strike.
Yet, Russia, like China, is also seeking to overcome US offensive and defensive capabilities by developing hypersonic weapons. In 2012, Deputy Prime Minister Dmitry Rogozin said that developing hypersonic technologies was a priority for the Russian military-industrial complex. Until now, the Russian Federation’s nuclear deterrent has consisted mostly of long-range ballistic missiles, launched from ground-based platforms or strategic submarines, as well as bombers armed with cruise missiles and shorter-range anti-ship and anti-air missiles. If these weapons could travel at hypersonic speeds, they could more easily overcome US (and NATO and Chinese) defenses.
A focus of Russia’s research has been on developing long-range, fast-flying cruise missiles that could help the Russian Air Force and Navy overcome superior US air and naval defenses. Through the BrahMos Aerospace joint venture, Russia has joined with India in developing cruise missiles for use by both their armed forces against land and naval targets as well as for possible export to other countries. The current BrahMos variant uses ramjet engines, which compress air using the forward motion of the engine. The joint venture is developing a BrahMos-II variant with scramjet engines that can conduct combustion at supersonic speeds and obliterate targets upon impact through kinetic energy.41 Although the Russian-Indian joint venture has yet to test a hypersonic weapon, in February 2015 BrahMos successfully test-fired a sea-based supersonic cruise missile thought to be the fastest in the world. It can travel at Mach 3 and has a range of 290 kilometers as well as the capacity to carry a warhead weighing up to 300 kilograms.42 In February 2015, Deputy Defense Minister Dmitry Bulgakov said that Russia had developed a “highly energetic” type of fuel that could propel the BrahMos-II to hypersonic speeds.43 BrahMos Aerospace’s CEO Sudhir Kumar Mishra claims that the BrahMos-II will be tested by 2017 and become operational at hypersonic speeds by 2023.44 Russia may also be developing a P-800 Onyx ramjet anti-ship supersonic missile, which is a more advanced version of the existing BrahMos-I, for possible near-term deployment on its s new Project 885 Yasen-class multi-purpose nuclear attack submarines. Although the Onyx has an estimated potential range of only 500 kilometers, it is intended to be highly maneuverable and fly in groups to better overcome any defenses through swarming and saturation tactics.45
Unlike Russia, China has concentrated its hypersonic R&D efforts on making “boost-glide” missiles akin to the US AHW. China has tested the Wu-14, which uses a large rocket booster to rise to suborbital altitudes (roughly 100 kilometers) and then fly back to earth at hypersonic speeds in a non-ballistic trajectory.46 The tested variant of the Wu-14 may have a shorter range than the US AHW.47 however, developing hypersonic systems of any range enables China to research and, therefore, better overcome US and other adversary hypersonic weapons. If China were to develop and deploy an operational hypersonic system, possible targets could include U.S. missile defenses, fixed military bases, and carriers and other warships.48 China could place both nuclear and conventional warheads on such systems, as the PLA does with its existing arsenal of ballistic missiles. Nonetheless, China still lacks the long-range global sensor coverage, equivalent to the US GPS satellite network, required for worldwide use of such a weapon. The current Beidou system cannot guarantee that navigational data would be available throughout the entirety of the boost-glide flight path; so China’s existing missiles must rely also on inertial and radar guidance.49 But China could more easily employ hypersonic systems against targets in Asia covered by existing Chinese sensors and intermediate-range missiles, such as US bases in Pacific countries and aircraft carriers.
The US Response
In November 2014, Defense Secretary Chuck Hagel launched a “Defense Innovation Initiative” to increase long-term investments in strategic technologies,50 saying that the proliferation of disruptive strategic technologies which previously only the United States had possessed, such as weapons of mass destruction and long-range ballistic missiles, was challenging the ability of the US military to operate in some foreign theaters. He called for a new “offset” strategy to enable the United States to stay ahead of potential adversaries such as China and Russia in critical military technologies, especially to overcome their A2/AD strategies. In Hagel’s vision, the first offset strategy was the US buildup of nuclear forces in the 1950s to negate the Soviet advantage in conventional military power, while the second was the drive during the 1970s and 1980s to develop new revolutionary technologies such as stealth, long-range precision strike, and enhanced intelligence, surveillance, and reconnaissance capabilities. He called for greater investment in such cutting-edge technologies as miniaturization, autonomous weapons systems, and advanced manufacturing techniques like 3-D printing in addition to the existing efforts in cyber warfare, directed-energy, electromagnetic railgun, and other strategic technologies. Although he soon left office, Deputy Secretary Robert Work has taken charge, making clear that the United States wants its allies, especially in Europe but also in Asia, to join in developing complementary capabilities.51
The Chinese and Russian progress in developing strategically disruptive weapons also raises the importance of efforts to make US military forces more “operationally resilient”—better able to defend against strategic attacks as well as to recover rapidly from them. Since World War II, the Pentagon has enjoyed a relatively secure global network of bases, but the proliferation of strategic weapons means that it increasingly needs to prepare to defend against, and recover from, attacks against its foreign bases, potentially at great distances from the immediate theater of war.52 Potential countermeasures include dispersing US forces over a wider geographic area, hardening military bases against attack, making systems less visible to adversaries through stealth and electronic countermeasures, and developing stronger defenses for land bases and large warships in the form of longer-range interceptor missiles as well as shorter-range laser and electromagnetic guns. Other options for parrying attacks include electronic and cyber countermeasures to disrupt an attackers’ navigation, communications, guidance, and other sensors as well as command-and-control capacities.53
Arms Control Possibilities and Problems
Russian leaders have argued that US development of strategically disruptive technologies such as hypersonic weapons, ballistic missile defenses, and cyber weapons makes it harder for Moscow to accept more cuts in offensive nuclear forces under any new arms control agreement. Both Chinese and Russians fear that the expanding US strategic capabilities threaten their capacity for assured nuclear retaliation and thereby undermine their capacity to deter a direct US attack or constrain US military interventions against other countries. Though US BMD systems would have difficulty coping with a full-scale Chinese or Russian missile strike, their task would be much easier following a US first strike that destroys many of the attackers’ missiles in their silos and, through kinetic or cyber strikes, disrupts their strategic command-and-control systems. In such a scenario, China or Russia might even refrain from a retaliatory missile strike against the US homeland since such a weak counterstrike could fail and provoke a full-scale nuclear response.
One way China and Russia can counter the risk of a US pre-emptive strike with conventional, nuclear, or cyber weapons, and of having their retaliatory missile strike weakened by US defenses, is to deploy more and better missiles and nuclear warheads, making them more capable of inflicting unacceptable damage on the United States. Yet, some of their responses can also be potentially destabilizing and encourage first strikes, including Russia’s construction of massive liquid-fueled missiles that are extremely vulnerable before launch, its arsenal of potentially thousands of tactical nuclear weapons, China’s co-location of its conventional and nuclear systems, or any launch on warning tactics. Furthermore, China and Russia are developing counter-space and offensive cyber capabilities designed to attack US command and control systems, which could contribute to inadvertent escalation in a crisis.
Of course, some strategic technologies could enhance strategic or crisis stability. For example, missile defenses can protect a country’s nuclear forces from a first strike, while cyber capabilities can bolster deterrence by augmenting threats of retaliation. Having multiple strategic retaliatory capabilities can reduce worries about technical or other vulnerabilities in a country’s nuclear deterrent. Whether a new military technology becomes strategically disruptive depends on its military impact, how rapidly it evolves, whether only one or many countries acquire that technology, and the theoretical prisms and operational constructs though which policy makers view the technology, among other, possibly unforeseen variables. Some of these conditions may be altered. For example, views of the potentially disruptive impact of strategic missile defenses have evolved over time. In many cases, they have been seen as weakening deterrence, but some have argued that they enhance deterrence.
It would be ideal to shape the deployment of potentially destabilizing systems with arms control agreements that constrain the most destabilizing capabilities and operational practices. In theory, some kinds of potential arms control agreements could reduce these problems. For example, China, Russia, and the United States could agree to limit the number of disruptive strategic weapons they deploy, prohibit the transfer of these technologies to third parties, and adopt rules to make it easier to determine if a system is armed with conventional rather than nuclear warheads by, for instance, keeping them in separate locations rather than co-locating them with shared command and control assets. The three could also cooperate more effectively regarding Iran, North Korea, and other sources of strategically disruptive threats.54 However, it would be challenging to agree upon and enforce these arrangements since disruptive technologies are, by their nature, rapidly changing. Furthermore, one reason why China and Russia are seeking disruptive strategic systems is to overcome US missile defenses; the United States has always resisted Chinese and Russian demands to limit the number, location, or capabilities of its BMD systems. In addition, the United States wants to retain the freedom to develop “hit-to-kill” BMD technologies and other countries, like China, want to keep pace with the United States
Whereas Moscow and Washington have negotiated bilateral arms control treaties for decades, Beijing has traditionally refrained from joining formal strategic arms treaties, and favors strategic ambiguity as a means of deterring a foreign attack. US officials have long sought strategic security discussions with China to promote military transparency and reduce misperceptions and mistrust. The focus of the China-US strategic dialogue has been on both countries’ nuclear forces and policies, but US officials have begun briefing the Chinese about BMD plans and programs. The US government is eager to discuss with China other capabilities that could affect mutual strategic stability, to include “space-related issues, conventional precision strike capabilities, and nuclear weapons.”55 The PLA has been improving its capabilities in all these areas, but so far these talks have been one-way, with the Chinese representatives listening with interest to presentations on US plans and programs but offering little information in return.
Despite the poor prospects for formal arms control agreements in these areas, opportunities for mutual and unilateral restraint exist. It is important to assure that decisions regarding the actual deployment of these capabilities are based on strategic criteria rather than simply technological opportunities—when plausible operational concepts for the use of these systems offer unique benefits whose net military and non-military advantages over costs exceed those of alternative capabilities.
I would like to thank the John D. and Catherine T. MacArthur Foundation for supporting his nonproliferation research and Justin Blaszczyk, Scott Goosenberg, Seungeun Lee, and Joel Max for their assistance in preparing this article.