Chris Newton is a former defence adviser in the Conservative Research Department.
At a time of strategic uncertainty, no decision in government can be more important than whether to replace the nuclear deterrent. In opposition, the Conservatives said that the policy was settled and that they would exclude Trident replacement from consideration in the Strategic Defence and Security Review (SDSR). But since the election, the issue has seldom been out of the headlines - including during this week's Liberal Democrat conference. The Chancellor’s decision to fund the costs of Trident replacement from the defence budget and not the Treasury has re-opened the debate on the matter both inside and outside the Party.
The arguments in a favour of a nuclear deterrent have been covered more than adequately in other articles. (I discuss future threats in Defence Viewpoints which can be found here.) This article will therefore focus on what type of nuclear deterrent we should have.
There is no doubt in my mind that the submarine deterrent based on a ballistic missile system is the best option. It is understandable that Liberal Democrats and others would want to find "cheaper" alternatives in the current financial climate. However, when you look at the evidence available, the Trident system not only provides the most effective deterrent, but also offers the best value for money and the best insurance policy for the taxpayer. Moreover, the various counter-arguments against a like-for-like replacement contain serious flaws.
Why can’t we just have a cruise missile alternative?
The Liberal Democrats have already ruled out land and air based alternatives. These options would involve the building of new infrastructure and platforms, which would be incredibly costly; and the platforms themselves would be vulnerable to a pre-emptive strike.
The Liberal Democrats are mainly pinning their hopes on using the Astute class attack submarine as a platform to fire nuclear cruise missiles. My main worry about this option is not just that cruise missiles are technically inferior to ballistic ones, and the question marks over the cost and legality of developing what would be a whole new system. It is that each time a conventional cruise missile was fired from a submarine, an enemy state would question whether it is a conventional one or a nuclear one. It is not difficult to see how a conflict could quickly escalate if an adversary made the wrong assumption.
Can’t we just have a part-time or ‘virtual’ deterrent’?
Currently nuclear deterrent submarines operate on what is known as a "continuous-at-sea deterrent" (CASD) basis. Some commentators have suggested that we should procure only one or two submarines and that these should patrol only part of the time. However, this is incredibly dangerous. The removal of a continuous-at-sea posture would create inconsistency and uncertainty in our policy, ultimately undermining our deterrent’s credibility. Furthermore, if a government decides to change its nuclear posture during a major crisis, it will risk escalating the situation further.