MICHAEL PORTILLO elegantly summarises all the dilemmas associated with updating Trident (Brown reaches for nukes just when they look nuts, Comment, last week). However, he spoils his argument with the conclusion that “we need new doctrines because the enemies that we must deter . . . are different from the past”.

True — but doctrine can be rewritten, if need be, every year to meet changing external circumstances. However, a British nuclear deterrent cannot be so magically reproduced at such short notice. With the relative vulnerability of an air-launched solution and the almost certain political unacceptability of UK land-based missiles, the submarine solution remains by far the strongest option. It also, inevitably, given the complexity of the launch platform, takes the longest to deliver and is far from cheap (whatever the trade-offs possible between numbers of missiles, warheads and boats).

For the UK then, a nuclear deterrent remains that expensive and bespoke insurance premium no government would ideally (and understandably) like to pay. Prudence probably dictates though that it should.

John Gardner
(Special Adviser, MoD, 1991-2), Thames Ditton, Surrey

FACT AND FISSION: Portillo says that nuclear weapons have a dubious deterrence efficacy, citing the actions of Galtieri on the Falklands and Nasser at Suez.

The point in both these instances was that there was never any possibility of the nuclear option being used — spoken about, maybe, but in reality both these generals knew it was not going to be deployed. This emboldened Nasser to continue; Galtieri had no choice, due to domestic pressure, but to chance his arm against a conventional military response.

Besides, I have always suspected there is a lot in Sir Humphrey Appleby’s remark, in the comedy series Yes, Prime Minister, that we possess our own nuclear arsenal largely because the French have one.

Paul Fairley
Surbiton, Surrey