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A Disturbance in the Force: Debating Continuous At-Sea Deterrence

Hugh Chalmers
Occasional Papers, 30 January 2014
Proliferation and Nuclear Policy, Trident, UK, Proliferation and Nuclear Policy
The UK might not need submarines continuously at sea to retain a credible nuclear deterrent, though adjusting to such a novel approach would carry risks

The fleet of Vanguard-class submarines that currently operates this tag-team patrol, known as continuous at-sea deterrence (CASD), will eventually retire to be replaced by a successor. While current UK policy states that a replacement fleet will take up this baton and maintain CASD for the foreseeable future, this will not be without cost.

This paper contributes to the debate over CASD by discussing how the practical application of non-continuous patrolling can affect the three main issues outlined in the TAR. To do so, it presents the role CASD currently plays in the UK’s nuclear posture, and describes the alternatives that have been proposed so far. It then addresses the three issues described above in turn, by detailing how the risks of inactivity and vulnerability evolve in smaller submarine fleets, and discussing how the fleet’s activation or deactivation might affect, and be affected by, the broader international context.

This paper argues that if the UK can develop procedures for activating, sustaining, deactivating and repairing a smaller fleet of nuclear submarines, which are simultaneously flexible and reliable, then many of the risks of noncontinuous patrolling postures could, in principle, be mitigated.

However, questions remain over how achievable this aim really is. Having spent forty-five years maintaining a continuous patrol, the UK has very little experience dynamically adjusting its patrolling schedule in line with an evolving threat environment. Furthermore, developing procedures to do so would naturally have to draw from an understanding of when the UK might wish to call upon its nuclear force: something the UK has so far only outlined in the vaguest possible terms.

About the Author

Hugh Chalmers is a Research Analyst within RUSI’s Nuclear Analysis Programme.

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