British and French nuclear submarine sharing

There have been discussions in recent months about the possibility of the United Kingdom and France sharing nuclear submarine patrols. Both countries maintain a policy of 'continuous at-sea deterrence' whereby at least one ballistic missile nuclear submarine is at-sea at any given time, usually in the Atlantic. The theory goes that by maintaining a continuous at-sea presence you ensure invulnerability and enhance deterrence. This is an expensive exercise (as was noted in the recent U.K. general election campaign) that drains significant resources from defence budgets. Many have also argued, with good reason, that it's an anachronistic cold war policy that has little utility against modern day threats.

As a possible alternative, individuals in France have suggested that the two nuclear states begin 'deterrence-sharing', with officials from both countries having discussed the proposal. However, it appears that the U.K., in particular, has been lukewarm to the idea. This is surprising given that it's the U.K. where the debate over the cost of nuclear deterrence has been raging. Here are some of the arguments for and against this proposal:

Arguments for:

1) Shared threats

Both countries face the same threats -- something that is widely acknowledged. This makes the plan conceivable from an operational standpoint as a nuclear threat to one is almost certainly a nuclear threat to the other.

2) Financial savings

The most obvious advantage appears to be cost. If the two countries share patrols - perhaps on an alternating basis - then they don't need to maintain four nuclear submarines each (as is currently the case). However, although there are savings to be made from operational costs, it should be remembered that much of the expense in building a fleet of submarines comes from the research and design phase. This means that the net saving from building three submarines instead of four is significantly less than 25 percent.

3) Advancing the multilateral disarmament agenda

Although the financial savings may not be huge, we should also consider the symbolic significance of further reducing submarine fleets and nuclear warheads. It would provide a boost to the perception among non-nuclear weapon states that the recognised nuclear powers are living up to their end of the NPT nuclear bargain. Therefore, the fact that the proposal would allow for a further draw-down in warhead numbers means it should be given serious thought.

Arguments against:

1) Operational questions

Although the proposal is conceivable in theory, there are some serious operational questions that would need to be answered. For instance: who would give the launch order? Could the French government overrule a U.K. order to one of its Trident submarines? This last question is especially pertinent if the crews of each submarine continued to be manned entirely by one nation. These problems could be overcome, but they represent a significant bureaucratic obstacle.

2) Sovereignty and domestic opinion

What is surprising about this proposal is that it came from France. Historically, Paris has been very attached to its nuclear deterrent as a symbol of national independence that enables it to conduct an autonomous foreign policy -- a well-known fact that has been acknowledged by a number of respected French scholars such as Bruno Tertrais. As a result, I don't think we can assume that this proposal enjoys wide support throughout the French government. Nor is it likely to be supported by the majority of the French public, who are also attached to the country's independent nuclear deterrent (I could be wrong on this point). Of course, similar questions apply within the United Kingdom as well, but I suspect that the opposition there primarily comes from governing officials rather than the general public.

3) Anglo-American nuclear cooperation

A further obstacle standing in the way of effective implementation on the British side is the country's Mutual Defence Agreement with the United States. This agreement forms the back-bone of extensive nuclear cooperation between the two countries, which includes scientific cooperation, warhead design, and the British purchase of the Trident missile. While it is possible that the proposal can be framed in a way that does not lead to any sharing of expertise between London and Paris, the United States may still have some concerns.

Overall this seems to be an interesting concept for which there are clear arguments on both sides. Time will tell if it gets any traction and is debated more widely, particularly in the context of the upcoming U.K. Strategic Defence Review. To be honest, it's probably unlikely. But if a wider debate does come about then the key argument in favour should be the furtherance of the multilateral disarmament agenda and not financial savings.