How much is enough? The 2018 Nuclear Posture Review and the value of nuclear parity

By Alexandria Reid


The underwater Baker nuclear test, Bikini Atoll, 25 July, 1946 (Credit Image: Wikimedia Commons)

The release of the Trump Administration’s Nuclear Posture Review (NPR) on 2nd February marks a decisive shift from the Obama Administration’s approach to nuclear weapons. Responding to a ‘dramatic deterioration of the strategic environment’ since the last review was published in 2010, this NPR contains a particularly notable departure in US nuclear strategy: the intention to further develop low-yield non-strategic nuclear capabilities. Unsurprisingly, the Pentagon’s determination to supplement the already extensive US arsenal with lower-yield warheads has stimulated a fierce debate on the logic of nuclear deterrence. Most importantly, it has raised questions about whether the world’s preeminent military power really needs a like-for-like arsenal to credibly deter a nuclear opponent.

This calculation is fundamental to the everyday practice of deterrence. Since the advent of the nuclear age at the end of the Second World War, debates about the trade-offs between the quantity and quality of weapons required to deter an adversary have dominated discussions about the composition of the ideal arsenal. Overall, estimates about the number of nuclear weapons required to deter an opponent have generally become more conservative since the end of the Cold War. Times have changed since in the crudest of Cold War calculations, Secretary of Defense Robert McNamara once judged that the US would need the capacity to eliminate between 20 and 25 percent of the Soviet population, and destroy 50 percent of its industry in order to deter the USSR from a first strike. Contemporary advocates of ‘minimal deterrence’ now hold the position that because of the unambiguously destructive quality of nuclear weapons, very few weapons are actually required to deter a rational opponent. Unsurprisingly, universal consensus on the ideal recipe for deterrence remains to be found.

Estimates of the number of weapons necessary still vary between single digits to hundreds, or even thousands of warheads. Crucially, advocates of minimal deterrence assert this small arsenal must survive a second strike so that a retaliatory threat of punishment is credible in the event of a first strike. To retain second strike capability, the nuclear platforms generally recommended are a combination of ballistic missile equipped submarines (SSBN), mobile intercontinental ballistic missiles (ICBMs) and strategic bombers carrying a variety of missiles (ALCMs). The US nuclear triad continues to be built on this model.

Yet many critics have long been concerned that the deterioration of the global threat environment means that a small number of weapons is not large enough to fulfil the multiple responsibilities assigned to the US arsenal. After all, US nuclear deterrence extends to both allied territories and the central deterrence of the American homeland. Keith Payne therefore argues that a credible minimum deterrence approach is based on ‘ideologically driven arguments’ that collapse when confronted by ‘cold reality.’ Yet as evinced by the NPR, the Trump Administration is less preoccupied with the US ability to achieve overall parity in nuclear weapons at a strategic level, and more concerned with a lack of like-for-like parity in low-yield nuclear weapons, sometimes referred to as ‘tactical nukes’.

It is clear from the NPR that the development of these low-yield warheads is mainly aimed at deterring any limited use by Russia in a regional conflict. Citing numerous Russian statements, the NPR refers to the fact that since 2000, Russian doctrine has reserved the right to employ low-yield weapons in a ‘de-escalation’ strike ‘in situations critical to the national security of the Russian Federation and its allies’. This includes a scenario in which Russia finds itself losing in a conventional regional conflict. In 2010, this doctrine was refined to only allow the use of nuclear weapons when ‘the very existence of the state is placed under threat’. Ironically, this mirrors the Flexible Response strategy adopted by NATO at the height of the Cold War in 1967. Motivated by its inferiority in terms of conventional forces, NATO’s strategy was to meet any Soviet aggression in Europe ‘with a credible threat of escalation in response to any aggression below the level of a major nuclear attack.’

With Russian revisionism back on the cards, the Trump Administration’s policy shift is motivated by the belief that the US force structure should be able to credibly deter this ‘de-escalation’ strike with a proportionately lower-yield weapon. Washington therefore intends to introduce two new capabilities into its arsenal: a low-yield warhead for the existing Trident D-5 (a submarine-launched ballistic missile, or SLBM), as well as the development of a new submarine launched cruise missile (SLCM). The NPR explicitly links this procurement drive to ‘correcting’ the Russian perception that there is a ‘coercive advantage’ in using nuclear weapons at lower – i.e. tactical — levels of conflict. Whilst maintaining a commitment that these weapons are not meant to enable nuclear war-fighting, this NPR clearly considers the use of non-strategic nuclear weapons to be politically viable as they appear to be a more proportionate response. Some have therefore suggested this development lowers the nuclear threshold in international politics today.

The merits of a low-yield nuclear response to a de-escalation strike make for a polarised discussion. The Trump Administration is by no means the first to recognise the strategic rationale for the development of non-strategic nuclear weapons. Indeed, several theorists in the eight years since the 2010 NPR was published have advocated this position, worried that the US would find itself ‘self-deterred’ in the event of a limited nuclear strike. With an arsenal equipped with only disproportionately large-yield nuclear weapons, some believe the US would be cornered into a situation of ‘surrender or suicide’.

Others are less enthralled with the idea. Nuclear theorist Adam Mount suggests that it would be in the US interest not to respond with nuclear retaliation even in the event of a limited nuclear strike by Russia. Instead, he suggests that the US would be better served by utilising its overwhelming conventional strength in battle, therefore strengthening the nuclear taboo and proving that there can be no political utility in the use of nuclear weapons for coercion. Meanwhile, although Survival’s Matthew Harries concedes that the Trump Administration’s assessment of the threat landscape is understandable, he argues that it would be a ‘thoroughly stupid idea’ for Russia to be the first country to deploy nuclear weapons since 1945. If Russia really were to use a nuclear weapon in Europe, it would surely become an unrivalled pariah state. In line with Harries’ argument, it’s easy to see it would be a thoroughly stupid idea for America to become the second country to use a nuclear weapon since 1945. A retaliation by nuclear counterattack would surely do more to undermine American global leadership than all of Trump’s foreign policy combined.


Alexandria Reid is a recent graduate of Conflict, Security and Development at King’s College London, funded by a Sir Evelyn de Rothschild Scholarship. She was recipient of the Sir Michael Howard Award for Best Graduate in BA War Studies, 2016. Alex currently works for Strife Blog as Communications Manager, and as a research assistant for Professor Michael Rainsborough. Twitter: @AlexHREID.

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