HL Deb 10 March 1981 vol 418 cc105-8

2.49 p.m.

The Earl of Kimberley

My Lords, I beg leave to ask the Question which stands in my name on the Order Paper.

The Question was as follows:

To ask Her Majesty's Government in what respects the Trident I missile system differs from the Polaris system.

The Minister of State, Ministry of Defence (Viscount Trenchard)

My Lords, the Trident I missile, like the Polaris missile, is a submarine launched, inertially guided, ballistic missile. It differs in that it is larger—2 feet longer and 20 inches wider—has three rocket motor stages compared with two, and has a range of 4,000 nautical miles with a full payload, compared with 2,500. It is designed to carry up to eight independently targetable warheads compared with the three warheads in Polaris which are not independently targetable.

We need these differences to maintain invulnerability against increased anti-submarine threats and to maintain penetration against improved anti-missile defences. The future effectiveness of our deterrent depends on this modernisation.

The Earl of Kimberley

My Lords, I thank my noble friend the Minister for that Answer. I wonder whether he can elaborate. Is it the case that Trident will enable us to strike enemy missile sites and thus lead to a new strategic doctrine of more feasibility in warfare?

Viscount Trenchard

My Lords, I am grateful to my noble friend for giving me this opportunity of going into a fraction more detail than I was able to in reply to the debate introduced by the noble Lord, Lord Chalfont, on 25th February. The Trident I missile, known as the C4, which the United Kingdom is planning to buy, does not have the precise accuracy needed to engage Soviet missile silos. This was made quite clear in the report to Congress in January of the outgoing United States Defense Secretary, which stated that today's sea-based strategic forces are ineffective against missile silos.

Lord Peart

My Lords, will the noble Viscount explain the difference in costs, and how that has been taken into account?

Viscount Trenchard

My Lords, in the debate on 25th February, and in the debate since then in another place, the question of costs has been gone into in depth. I believe that that is another question, and, if the noble Lord would like to put it down, I should very much welcome the opportunity of once more stating in detail the fact that we believe this to be the most economic answer for maintaining an effective British strategic deterrent through the 'nineties and into the next century.

Lord Shinwell

My Lords, will the noble Viscount the Minister be good enough to recall in a recent debate the thoughtful and penetrating speech by the noble Lord, Lord Chalfont, on the subject of the Trident, when he appeared to cast some doubts on its validity and its capabilities? Is it at all possible in an assembly of this kind, with the utmost respect to Members of your Lordships' House, to come to a definite conclusion about the comparative values of the Polaris of the past and the possible Trident of the future without having available every technical and technological detail? Is it at all wise, with all the uncertainty and tension that exists in the international sphere, to spread doubts about the inefficiency, or suggested inefficiency, of a missile, a weapon, which might make all the difference between surrender to an aggressor and our security?

Viscount Trenchard

My Lords, I thank the noble Lord for those supplementary questions. We did have a very good and deep debate introduced by the noble Lord, Lord Chalfont, a week or two ago. I believe that in this House we should be able to get very much closer to an agreed view, and I shall certainly work, both in the House and with the committees of the House, in trying to arrive at that situation. I agree entirely with the noble Lord that there is no need to cast doubt either on the current effectiveness of our Polaris deterrent, or, in my view, on the effectiveness of the modernisation of that deterrent which will come in with Trident.

Lord Chalfont

My Lords, may I ask the Minister if he will confirm that in his reply he was referring exclusively to the Trident C4 missile? Will he also confirm that it is not the intention of Her Majesty's Government to acquire the D5 missile, which is equipped with ten warheads, not eight?—the Mark 12A warhead, which has an accuracy of 400 feet and is specifically designed for the destruction of point targets such as Soviet missile sites.

Viscount Trenchard

My Lords, I am grateful that the noble Lord has himself intervened. Yes, I am talking of the C4 Trident I missile, which is the missile about which we have reached agreement in principle with the United States, including broad estimates of costs on which our cost estimates are based, for the continuation of the British strategic independent deterrent. The Trident II missile to which the noble Lord now refers—and I am glad to have, if I have it, his confirmation that it was to this missile that he was referring in his debate—is still very much at the development stage. I understand from the United States Defense Department that its full characteristics are not yet entirely decided, and it has not been the subject to date of any discussions between Her Majesty's Government and the United States. I should not like to rule out such a strategic missile for this country for all time, but the decision so far is to modernise, and keep effective to the same degree of deterrence as we have had in the past, through the 'nineties and into the next century.

The Earl of Onslow

My Lords, will the submarine being built for the C4 missile be capable of carrying the D5 if Her Majesty's Government agreed that it had become necessary, and would this involve very great extra cost?

Viscount Trenchard

My Lords, that again, if I may say so, is a separate question, and not one to which we have addressed ourselves at this stage.

Lord Orr-Ewing

My Lords, will my noble friend, when he comes to answer about costs, point out to the House the cost of the Tornado programme, which appears to be three times as much as the present planned cost of the introduction of Trident? And will he perhaps confirm to the House that this Government will plan down to the cost of £5,000 million while at the same time keeping an effective deterrent through the years until 2010?

Viscount Trenchard

My Lords, if my noble friend will allow me to keep my powder dry for a separate question on the matter of costs, I will answer in detail at that time. But certainly the Tornado programme has been more expensive, or will have been more expensive, than the estimates of the Trident I deal overall. Certainly we believe that the Trident I deal is perfectly accommodatable, if that is not a terrible word, in terms of our defence budget as a whole in more or less the same way as we have accommodated Polaris and previous independent deterrents.

Lord Brockway

My Lords, may I ask the Minister whether there are not three differences: first, is not the cost greater, as my noble friend Lord Peart has indicated; secondly, is it not much more an offensive weapon than a defensive weapon; and, thirdly, will it not intensify the arms race in the world when there is now some hope of disarmament, in the United Nations Geneva Committee, in the Madrid Conference for a European Disarmament Conference, and in the proposals of Mr. Brezhnev for a summit conference?

Viscount Trenchard

My Lords, I do not accept the noble Lord's premise, any more than the Government did in Lord Chalfont's debate, that the Trident I is a greater cost. It is over a longer timespan and it is for a system to last for a longer period. I do not agree that it is different and more offensive, for the reasons that have perhaps been touched on in the questions today. We shall certainly, as is our constant policy, lose no opportunity to intensify moves towards arms control, and, if they can be made effective on both sides, the cost of investments that have previously been made will not deter us from moving towards a more peaceful world at a lower balance of arms.

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