3. What conclusions he has drawn from the Trident alternatives review about alternatives to a UK nuclear deterrent based on Trident. (900042)

9. What conclusions he has drawn from the Trident alternatives review about alternatives to a UK nuclear deterrent based on Trident. (900048)

11. What conclusions he has drawn from the Trident alternatives review about alternatives to a UK nuclear deterrent based on Trident. (900051)

The review demonstrates that no alternative system is as capable as a Trident-based deterrent, or as cost-effective.

Does my right hon. Friend agree that one of the dangers of the alternatives to Trident is that of mistaken identity? An intercontinental ballistic missile leaves a very distinct signature on launch, whereas the alternatives could be confused with conventional weapons, and hence trigger an escalation rather than a de-escalation of conflict.

My hon. Friend is absolutely right. The Trident alternatives review makes clear that that is just one of the many drawbacks of a cruise-based system. The other primary drawbacks are the risk, the time scale for development, the likely cost, the lack of range, and the vulnerability of the weapons system.

Will the Secretary of State confirm that, when maintenance is taken into account, the cost differential between four boats and three boats is minimal, and that we should press ahead with a full replacement for Trident because it is in our national interest to do so?

My hon. Friend has conflated two different questions. The Trident alternatives review states categorically that Trident provides the best value and the best capability for the United Kingdom. As for the separate question of how many boats are needed, the Government are determined to maintain continuous-at-sea deterrence, and the best advice at present is that that will require four boats. The cost differential between three and four boats is about £1.7 billion in net present value terms, or about £50 million to £60 million a year over the life of the project.

My right hon. Friend has already made a powerful case for Trident and for continuous-at-sea deterrence, but does he agree that other potential deterrents that have been mooted, such as an airborne deterrent, would also be expensive to implement? Moreover, an airborne deterrent would be prey to a pre-emptive strike—which means that it would be no deterrent at all—and would be considered objectionable by many people who do not want nuclear armed planes landing and taking off on their doorsteps.

Indeed. The nature of the United Kingdom, which is a relatively small and densely populated land mass, is one of the factors taken into account by the Trident alternatives review, and one of the reasons why the idea of land-based ballistic missiles was ruled out at an early stage. The review states clearly that all alternatives to Trident are less capable, higher-risk and more expensive. That strikes me as a pretty categorical conclusion.

Can the Secretary of State tell the House how much taxpayers’ money has been spent on the Liberal Democrat vanity project that is the Trident alternatives review, given that, by and large, both the Conservative part of the coalition and the Labour Opposition support the outcome and knew what it would be?

I can tell the right hon. Gentleman that the work on the review was conducted in-house, led by the Cabinet Office and supported by the Ministry of Defence, and that the principal cost involved will have been civil servants’ time. If he submits a written question to me, I will ask the Department to produce the best estimate that it can make of the time involved.

Does my right hon. Friend agree that if we opted for an alternative to Trident, we should probably have to be out of the submarine building business altogether, and that that would pose a real risk to the national security of the country?

My right hon. Friend has made an extremely good point. It seems often to be forgotten by those who advocate an alternative that we must make a choice about whether to sustain a submarine building industry in the United Kingdom. I, for one, believe that it is essential to the UK’s strategic interest for us to maintain a submarine-building capability, and that further points to the use of a submarine-based continuous-at-sea deterrent.

The Government’s Trident alternatives review covered a large number of options and was described in this House by the Chief Secretary to the Treasury as the “most comprehensive study” of our nuclear deterrent policy. Will the Secretary of State enlighten the House as to why the alternative being put forward now by the Liberal Democrats of two boats conducting irregular unarmed patrols was not considered as part of that comprehensive review?

The review considered a three-boat alternative and a four-boat alternative; it did not consider a two-boat position, as that was not considered a credible deterrent.