Conventional Arms Control and Nuclear Security: The Challenge of Conventional Prompt Global Strike Weapons

The strategy of nuclear deterrence is changing, and Conventional Prompt Global Strike (CPGS) weapons are making it more complicated.

What are CPGS Weapons?

CPGS systems are conventionally armed weapons that can accurately strike a target anywhere in the world within one hour of the decision to launch. Of the various types of CPGS weapons that exist, U.S. development in CPGS systems is increasingly focused on hypersonic, rather than ballistic, variants. To be effective, these relatively low yield weapons are not only fast but incredibly accurate as well. This accuracy is arguably the key factor, as developments such as super-fuze technology and the adding of GPS to conventional missiles have begun to enable conventional weapons to take on roles traditionally assigned to nuclear weapons. 

Traditionally, striking something on the other side of a planet was challenging due to inherent difficulties with accuracy, but one could compensate for this with a large enough blast from a high-yield, often nuclear, warhead. With this in mind, a disarming first-strike against a nuclear adversary and their hardened nuclear weapons would require the use of incredibly destructive, inevitably nuclear, warheads to ensure that the target was hit with enough force to prevent retaliation. However, this ungodly level of destruction effectively deters itself. Not only does it violently break the ever present nuclear ‘taboo’ beyond what anyone could justify as reasonable, but the environmental damage done to the planet from that many nuclear detonations could be catastrophic even before a second strike. In a strategic sense, this potential environmental catastrophe has arguably prevented the actual use of a disarming first strike against Russia or the U.S.  from being a viable or rational option.  

The Danger of a ‘useable’ Weapon

Despite being technically less destructive, conventional warheads lead to a new and unique set of dangers. These weapons are “useable” in the sense that they lack the well-deserved stigma that comes with nuclear weapons. Unlike a nuclear first strike that risked environmental devastation and shattered the taboo of non-use, a conventional first strike could theoretically destroy the nuclear deterrent of an adversary with minimal casualties which in turn makes a disarming first strike a real possibility. The useability of these weapons makes them uniquely dangerous as they can threaten an absolutely one-sided victory without the usual consequences of nuclear use. This changes the perceptions states have regarding the security of their, or an adversary’s, deterrent capabilities. 

Even if aggressive actions are unlikely to achieve victory, if conquest is believed to be      possible, then states will act accordingly. Conversely, those who would be on the receiving end of these weapons now feel compelled to adapt, often in ways that contribute to instability, to the increasing possibility of a conventional first strike on their nuclear deterrent. Within China the concern over a preemptive strike by the U.S. has led to serious discussions surrounding the scrapping of China’s long-standing policy on the No First Use (NFU) of nuclear weapons so that they could respond to a conventional attack with their nuclear deterrent. Additionally, the future trajectory of these weapons has caused a similar concern in Russia which is reflected in a recent state policy document on nuclear deterrence clearly outlining the right to use nuclear weapons in response to a conventional attack that either undermines their nuclear deterrent or threatened the existence of the Russian state.

The Answer is Arms Control

The development of accurate conventional weapons is somewhat inevitable as the improvement of accuracy is effectively bound to happen. Despite this, through careful and meaningful cooperation efforts, there are ways to mitigate this degradation of deterrence. While conventionally armed ballistic missiles fall under the purview of New START, hypersonic variants do not. Russia’s dual-use Avangard hypersonic boost-glide vehicle is launched using existing intercontinental ballistic missiles which is why it counts towards the limits placed under New START. If placed on a different type of rocket, the Avangard would no longer be limited. This is pertinent because of the U.S. focus on hypersonic CPGS weapons; while ratifying the New START treaty the U.S. made it clear that their interpretation did not set limits on hypersonic CPGS weapons. This acts as a loophole for the creation of strategic weapons which could tip the balance of power in a dangerous direction.      

It should be noted that it is the technology itself that is problematic rather than any particular state. Unregulated, CPGS weapons will create dangerous instability and act as a serious barrier to the meaningful disarmament of nuclear weapons. Setting limits on the number of CPGS weapons a state can have would help prevent states from attempting to achieve an offensive superiority. Additionally, limits could also ease the fears of adversarial states and result in more relaxed nuclear doctrines. Finally, having a concrete cap on the number of CPGS systems could contribute to the restart of meaningful disarmament as each party would know exactly how far they could reduce their nuclear arsenal before CPGS weapons could be used to conduct a realistic first strike. Reliable CPGS weapons are still a developing technology, but every major player is quickly developing these weapons and the day when they’ll start to play an active role in armed conflict isn’t far off. Factoring in and including developing conventional capabilities in arms control now will be instrumental for achieving disarmament in the future.  

Views expressed belong solely to the original author of the article and do not necessarily represent the views and opinions of BASIC. 

Peter Rautenbach is a graduate candidate finishing his MSc in International Relations at The London School of Economics and Political Science. There he has continued his work on topics surrounding nuclear security and deterrence. His particular passion has been to understand the strategic impacts of evolving technologies such as ballistic missile defence and conventional prompt global strike weapons. As his courses have officially come to an end, Peter has gone back home to British Columbia, Canada to finish his dissertation while enjoying the family farm and his horse Rogue.  

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