Polaris (Hansard, 26 July 1985)

§ Mr. Heseltine

The possibility of extending the useful life of our existing Polaris force well into the next century was considered, along with a range of other options, during the detailed evaluation which led to the882W Government's decision to purchase Trident as the successor to the current United Kingdom strategic deterrent force. The main aspects of that evaluation process were set out in Defence Open Government Document 80/23, which still remains essentially valid today.

In order to ensure that the Polaris force, now improved by the Chevaline programme, will continue to provide a credible deterrent until the mid-1990s when it is to be replaced by Trident, we are currently engaged in a missile remotoring programme. This programme has demonstrated many of the potential problems and expense of a project unique to the United Kingdom; nevertheless, we are confident that the outcome will be successful and that the remotored missiles will have a substantial life expectancy. It could be argued that the new motors might have provided a core stock for a future strategic missile system based on the Polaris model, but the missile motors are only one element of the missile, and of course a smaller proportion of the total weapon system.

To maintain the Polaris system as a credible deterrent beyond the turn of the century, it would have been necessary to replace all other missile associated components together with aging sub-systems such as guidance, fire control, missile launching and test equipment and to renew the whole range of related shore support and training equipments. It would also have been necessary to buy additional Chevaline elements to support the force, and to extend the life of missile processing facilities at the Clyde submarine base.

Even if a United Kingdom replacement programme on these lines proved successful, the overall weapon system effectiveness would not have given a sufficient assurance of credibility much beyond the 1990s. Because the range of a Polaris A3 missile is so much less than that of Trident. D5, submarines equipped with a Polaris-based system would have been constrained to operate in a much smaller sea area, in the face of Soviet anti-submarine warfare (ASW) capabilities, which are expected to improve over the next decade.

In addition, the Soviet Union is currently making substantial improvements to its anti-ballistic missile (ABM) defences within the provisions of the 1972 ABM treaty, as amended by the 1974 protocol. Unless these improvements fall well short of our expectations, the capability of the Chevaline payload will prove inadequate to overcome the ABM defences we expect to see deployed in the mid-1990s.

It would also be misleading to suppose that a force based on Polaris could be deployed without replacing the Resolution class submarines, which would all be over 30 years old by the turn of the century. The fact remains that by the next century we will require improved sonars and a modern propulsion system based on the new pressurised water reactor (PWR2) to enable us to stay ahead of developing Soviet ASW capabilities and to maintain the standards of invulnerability required from a strategic nuclear deterrent. Only a new class of submarine can meet this requirement.

As we indicated in DOGD 82/1, even if we had opted for a smaller missile than Trident D5 it would still have made sense to construct a submarine hull of sufficient size to cater for a larger missile at some time in the future. Moreover, we have had no capability in the production of strategic weapon systems since the 1960s, and the research 883W and development programmes and subsequent flight trials would have taken a great deal of time and would have entailed considerable risks.

Doubts might also have been cast on the credibility of a unique United Kingdom system. For all these reasons it is therefore doubtful whether the capital cost of a new Polaris missile-based system would have been any cheaper than our Trident D5 force, and through-life running costs would almost certainly have been considerably higher, all this for a much less effective system.

With Trident D5 we will be continuing the highly successful co-operation with the United States which we have enjoyed for over two decades. It is our safest, wisest and most cost-effective course.