The independent resource on global security

Time to factor missile defence into nuclear arms control talks

US-missile-defense-system-intercepts-ICBM-target-in-test
US missile defence system intercepts ICBM target in test. Photo: Missile Defense Agency/Lisa Simunaci
Dr Tytti Erästö and Matt Korda

Hopes run high that the possessors of the world’s largest nuclear arsenals—Russia and the United States—might finally resume negotiations on nuclear weapon reductions after over a decade of diplomatic deadlock. Some essential building blocks have already been laid: In February 2021 the two countries extended the 2010 Treaty on Measures for the Further Reduction and Limitation of Strategic Offensive Arms (New START) for five years and in July 2021 they started what is intended to be a ‘deliberate and robust’ Strategic Stability Dialogue ‘to lay the groundwork for future arms control and risk reduction measures’.

It is unclear whether this new determination to move towards arms control is ultimately sufficient to resolve deep-seated strategic disagreements, the most difficult among them being the Russian–US dispute over missile defence. A failure to tackle this persistent problem may well prevent any breakthroughs. Yet an agreement on missile defence limits could open the door to significant nuclear weapon reductions. At the same time, it could indirectly help address key drivers behind Chinese nuclear expansion—illustrated most recently by the construction of new long-range missile silos across the country.

Strategic offence–defence balance during the cold war

It is hard to imagine nuclear arms control during the cold war without the 1972 Anti-Ballistic Missile Treaty (ABM Treaty) between the Soviet Union and the USA. The ABM Treaty came about in response to attempts by both countries to develop large-scale strategic defences against intercontinental ballistic missiles (ICBM) in the 1960s. By the early 1970s they had reached the conclusion that such systems could not realistically defend against a massive nuclear attack; however, their pursuit would create doubts about the survivability of both parties’ second-strike nuclear forces. This could further accelerate the arms race, by prompting each side to further build up its stockpile of offensive weapons.

Through the ABM Treaty and its additional protocol, each side agreed to maintain only one strategic missile defence site with up to 100 launchers and 100 interceptor missiles. Binding limits on strategic missile defence systems were viewed by both parties as ‘a substantial factor in curbing the race in strategic offensive arms’. The ABM Treaty thus laid the basis for limiting nuclear arsenals; it was negotiated in parallel with the Strategic Arms Limitations Talks (SALT I) that led to the first-ever nuclear arms control accord—the 1972 Interim Agreement.

The Soviet–US consensus on the balance of offensive and defensive forces was shaken in the early 1980s by the then US president Ronald Reagan’s Strategic Defense Initiative (SDI). The SDI sought to make the USA invulnerable to nuclear attacks by intercepting ICBMs in space. Dispute between the two countries over the SDI stymied historic 1986 nuclear disarmament talks in Reykjavík, where the Soviet Union and the USA discussed the elimination of their entire nuclear arsenals. Disagreement about a seemingly minor detail of SDI-related testing appeared to prevent complete nuclear disarmament. In 1987 the two countries nevertheless took a much less ambitious, yet still significant, step towards disarmament by signing the 1987 Treaty on the Elimination of Intermediate-Range and Shorter-Range Missiles (INF Treaty).

Russian–US tensions over missile defence after the cold war

Since the end of the cold war, no Russian–US nuclear negotiations have included comprehensive plans for nuclear disarmament. Instead, the focus has been on gradual reductions in deployed strategic weapons, starting with the 1991 Treaty on the Reduction and Limitation of Strategic Offensive Arms (START I). After having abandoned the SDI as unfeasible, in the 1990s the USA shifted its focus to regional missile defences. Although this issue initially complicated the START II negotiations, it was settled with the 1997 demarcation agreements, which sought to ensure that regional missile defences would not undermine strategic stability. However, the subsequent renewal of US interest in strategic missile defence led it to withdraw from the ABM Treaty in 2002. This has had major repercussions for efforts to limit nuclear weapons. One immediate impact was that START II never entered into force, as its ratification by Russia was conditional upon compliance with the ABM Treaty.

The USA justified its withdrawal from the ABM Treaty in terms of the perceived threat from what it called ‘rogue states’—US regional adversaries like Iran, Iraq and North Korea. President George W. Bush’s administration argued that such states could develop nuclear-armed ICBMs and might not be deterred in the same way as US nuclear peers. Given the ‘reality that the cold war is over’, Bush even suggested that discarding the ABM Treaty would be consistent with ‘further cuts in nuclear weapons’. That assumption has hardly stood the test of time.

In contrast, Russian officials continued to regard the ABM Treaty as the ‘cornerstone of strategic stability’. President Vladimir Putin noted in 2000 that ‘the mutual reduction of strategic attack weapons . . . is possible only when the ABM Treaty continues to hold’. Its abrogation, he continued, would force Russia ‘to look for an alternative to end its commitments’ under START I and the INF Treaty.

Over the last 20 years, the USA has expanded both strategic and regional missile defences. In addition to 44 strategic ground-based interceptors (GBIs) on the US mainland, it has built regional missile defence systems in cooperation with allies, including in Europe. The USA initially planned to deploy strategic defences in Eastern Europe against hypothetical Iranian ICBMs. Russia bitterly resisted this, leading to the culmination of the missile defence dispute prior to the New START negotiations. The dispute contributed to President Barack Obama administration’s 2009 decision to scale down the European missile defence plans into a shorter-range Aegis system, developed under the North Atlantic Treaty Organization’s (NATO) auspices. In this context, NATO and Russia also explored possibilities for missile defence cooperation. While falling short of Russian demands for legally binding limits on missile defence, these developments created a thaw in the dispute that facilitated the conclusion of New START in 2010.

However, the discussion on missile defence cooperation ended in disagreement and tensions soon resumed. The then Russian president, Dmitry Medvedev, warned in 2011, that continued failure to resolve the dispute would lead Russia to take countermeasures, such as equipping its ‘new strategic ballistic missiles . . . with advanced missile defence penetration systems’. Russia also reserved the right to ‘discontinue further disarmament and arms control measures’ and consider ‘withdrawal from the New START Treaty’—only nine months after its entry into force. Additionally, Russia would deploy modern offensive weapon systems to ensure the ‘ability to take out any part of the US missile defence system in Europe’. Although Medvedev only specifically mentioned the Iskander short-range ballistic missile in this context, Russia’s subsequent deployment of cruise missiles can be seen to serve the same purpose. Indeed, ground-launched cruise missiles may be better suited to targeting missile defence sites in Poland and Romania than short-range ballistic missiles. The missile defence dispute may thus have contributed to Russia’s violations of the INF Treaty and the subsequent demise of the treaty.

Missile defence as a driver of nuclear armament

The dispute over missile defence seems to have become a significant driver of Russia’s nuclear modernization. In contrast to the cold war-era strategic stability considerations, Russia’s current concerns about missile defence are closely tied with the evolution of conventional long-range precision-strike capabilities, which could in principle enhance the potential for non-nuclear counterforce strikes in the future. Describing such a scenario in 2016 Putin said that ‘some high-precision weapons are used to carry out a pre-emptive strike, while others serve as a shield against a retaliatory strike, and still others carry out nuclear strikes’.

In March 2018, Russia unveiled its new suite of developmental nuclear delivery systems. These included a heavy ICBM with penetration aids, a modified ICBM with a hypersonic glide vehicle—which the Russian president described as ‘the most modern means of evading missile defence’—and a nuclear-armed unmanned underwater vehicle. Notably, five out of the six new systems are specifically designed to either evade missile defences or play a supporting role in other systems’ evasive manoeuvres. Putin explained that these had been developed in response to the ‘constant, uncontrolled growth’ of US missile defences, to avoid ‘the complete devaluation of Russia’s nuclear potential’.

The drivers behind the Russian modernization programme are, however, disputed. Some have suggested these Russian arguments are an excuse for a modernization programme driven by other factors, such as a desire to improve the destructive power of Russia’s nuclear arsenal or the quest for great power status. Russia’s concerns have also sometimes been dismissed on the grounds that its vast nuclear arsenal would outnumber US defensive interceptors. While true, this line of argument misses the tendency of strategic threat assessments to focus on future scenarios, which are influenced by a continued expansion of US missile defences. The argument also discounts the possibility of deep nuclear reductions—which would be difficult if Russia believes that a smaller nuclear arsenal is more vulnerable to US missile defences.

Others, while recognizing the underlying strategic stability problem, have suggested that it is not possible to limit missile defence through arms control, given the unwavering bipartisan support for missile defence within the USA. Recently, however, there have been stronger voices calling for such limits—not only to deal with the strategic dispute with Russia, but also to address growing concerns over China’s nuclear build-up.

Security ‘trilemma’

In parallel to Russia’s modernization programme, China has also been upgrading its nuclear arsenal. Traditionally, China has maintained a doctrine of ‘minimum’ nuclear deterrence based on a relatively small number of nuclear weapons. However, as reported in successive SIPRI Yearbooks, the country’s nuclear weapon stockpile has increased from 260 warheads in 2015 to 350 warheads in 2021. At the same time, China’s efforts to enhance its sea-based nuclear deterrent appears to be increasing the operational readiness of its nuclear weapons, as such weapons would need to be deployed on ballistic missile submarines to pose a credible threat. Earlier this year, concerns about Chinese nuclear expansion were further exacerbated by satellite images of new ICBM silo fields, which, once completed, could mean a ten-fold increase in the number of Chinese ICBMs.

Rather than a desire to match Russia and the USA, China’s nuclear upgrades seem to be driven by the perceived need to ensure the survivability of its second-strike capability. Reminiscent of Russian concerns, China explains the need to reinforce its nuclear deterrent based on the perceived threat from US missile defences and precision-strike weapons. As stated in a 2018 Working Paper by the Chinese Government, ‘The international community should pay attention to strategic issues that may have a negative impact on nuclear disarmament. Development or deployment of global missile defence systems should be stopped and abandoned immediately.’ The vulnerability problem with China’s second-strike nuclear forces appears particularly acute as its previous ICBM arsenal could have been outnumbered by US strategic interceptor missiles.

China’s reaction, as in the case of Russia, was foreseeable in light of previous statements. In the late 1990s, the then Chinese president Jiang Zemin noted that ‘deployment and proliferation of sophisticated anti-missile systems . . . would inevitably exert a negative impact on international security and stability, triggering new arms races and obstructing disarmament and nonproliferation efforts’. A 2002 report by the US Congressional Research Service also foreshadowed a future Chinese nuclear build-up as a potential consequence of the ABM Treaty’s demise. The report quoted warnings by Russian officials that ‘other nations, such as China, might believe that their offensive forces would be undermined by US defenses, and might feel compelled to expand their arsenals to ensure an effective retaliatory attack’. This could result in a security ‘trilemma’ whereby Russia and the USA would modernize their own arsenals in response to Chinese developments. As the report states, ‘many critics of missile defense . . . argue that, in the long run, the United States could become less secure with nationwide missile defenses than it is in its current more “vulnerable” condition’.

In hindsight, and with the worrying developments in both China and Russia, the 20-year-old prediction that enhanced missile defences could diminish strategic stability has certainly come to pass. There are even indications that China’s and Russia’s pursuit of their own missile defence systems are prompting corresponding reactions from other nuclear-armed states. In 2021, the United Kingdom’s Integrated Review announced a sudden increase to the upper limit of the country’s nuclear inventory. British Defence Secretary, Ben Wallace, specifically linked the change to Russia’s recent improvements in missile defence: ‘We have to . . . maintain a credible deterrent to reflect and review what the Russians and others have been up to in the last few years. We have seen Russia invest strongly in ballistic missile defence. They have planned and deployed new capabilities. That means if [the UK’s deterrent] is going to remain credible, . . . you have to make sure [warheads] are not vulnerable to ballistic missile defence.’

The need for limitations on missile defence

The USA has repeatedly voiced concerns about Chinese and Russian nuclear modernization programmes. It has sought to address those concerns by engaging in Strategic Stability Talks with Russia and, during President Donald J. Trump’s administration, by calling for trilateral nuclear arms control including China. At the same time, the USA has remained unwilling to consider limitations on its own missile defences, despite their prominent role in driving Chinese and Russian nuclear modernization.

The USA continues to argue that its missile defences are limited to addressing threats from so-called ‘rogue nations’, rather than nuclear peers. However, that all-important line has been blurred in recent years. In 2016 the US Congress subtly changed the wording of legislation describing the purpose of national missile defence as being ‘against the developing and increasingly complex ballistic missile threat’, dropping the previous formulation ‘against limited ballistic missile attack’. The Trump administration’s 2019 Missile Defense Review (MDR) maintained that the USA relies ‘on nuclear deterrence to address the large and more sophisticated Russian and Chinese intercontinental ballistic missile capabilities’. Yet it simultaneously included an explicit reorientation of US missile defences to address Chinese and Russian hypersonic threats. Furthermore, the 2019 MDR noted that, although the national missile defence system ‘is designed to defend against the existing and potential ICBM threat from rogue states such as North Korea and Iran, . . . in the event of conflict, it would defend, to the extent feasible, against a ballistic missile attack upon the US homeland from any source.’ Together with Trump’s assertion that US missile defence systems are intended to ‘detect and destroy any missile launched against the United States anywhere, anytime, anyplace’, the 2019 MDR seemed to validate the concerns of Chinese and Russian strategists, who largely never believed previous US assurances about the limited nature of the US missile defence efforts.

An opportunity for the USA

President Joe Biden’s administration has an opportunity to reformulate US missile defence policy in its upcoming MDR. The administration should seek to establish clear goals and firm limitations—rather than continue to develop the US missile defence architecture as an ever-evolving, open-ended project—and clearly communicate that policy to China and Russia. A comprehensive assessment of the entire US missile defence architecture, carefully measured against those goals and limitations, would help to determine which systems could be capped, scaled back or traded away under a potential arms control agreement. Such constraints might not even need to affect existing US missile defence capabilities, but rather limit further expansion. As Russian political scientist Alexei Arbatov has suggested, capping the US strategic interceptors to 200 might be sufficient to address Russian concerns. A Russian–US agreement on missile defence limits would also indirectly help address the strategic stability concerns behind China’s nuclear expansion in a situation where numerical disparity prevents multilateral arms control negotiations.

It is increasingly difficult to ignore the role of US defensive systems in triggering offensive reactions from other nuclear weapon states. The clearest path towards reining in Chinese and Russian nuclear programmes would be to place US missile defence systems on the bargaining table. This means overcoming formidable domestic obstacles in the USA. However, the potential security gains—curbing the current offence–defence arms race and enabling long-overdue progress on nuclear disarmament—would clearly outweigh the political costs.

ABOUT THE AUTHOR(S)

Dr Tytti Erästö is a Senior Researcher in the SIPRI Nuclear Disarmament, Arms Control and Non-proliferation Programme.
Matt Korda is an Associate Researcher with the SIPRI Nuclear Disarmament, Arms Control and Non-proliferation Programme and Research Associate with the Nuclear Information Project at the Federation of American Scientists (FAS).